I know, I know, you guys are all tired of subwoofer neophytes looking for buying advice...
But this post is different!
Well, maybe not that different, but I'll try to make this interesting...

I'm looking to buy a used sub. But if I put up a post with a $200-400 price range the advice I get will probably be about mostly low end stuff.

But what I'm looking for is a sub that makes three people cry:
1. Me, when I turn it on and it rearranges my internal organs with it's earthshaking (yet beautifully clear) bass
2. My neighbors, when they have to repair the cracks in their foundation and, most importantly...
3. The person I buy it from, when they realize they're selling it to me for a tenth of what they paid simply because their significant other told them to get that big ugly thing out of the house.

You see, I just bought a whole set of home theater speakers from a really nice guy who unfortunately has a wife that actually cares what their living room looks like. He now has a set of tiny, pretty and okay sounding speakers and I'm now blaring his original set of large, black, boxy ones. Did I mention that I paid less than a quarter of retail?

Now all I need is a sub. My old 10" Boston sub, and my old 10" Velodyne sub are okay, but I want more dammnit! Big! Boxy! Ballsy! Bargain!!!

It seems that more and more people are taking the flat panel TV disease and spreading it to their speakers. No more surrounding yourselves with big black boxes and taking off the grills. Now it's all about hiding them in the wall, or behind a potted plant in your living room.
Not me.
I still have a dark, dedicated HT room that my wife (so far) has let me keep.
I know a fair bit about TVs, and a little about speakers, but very little about subs. I trust most of the folks on this board. What should I be on the lookout for?
Here's some info for those of you nice enough to give me some advice (I don't even need actual model numbers, just give me a range and some brands)

1. Price range. $200-400 (but that's a craigslist price, meaning the sad desperate sucker... oops, sorry, "original buyer" - paid anywhere from $500-$3000).
2. Size is not an issue. Neither is appearance. If it looks like a fifty gallon drum but has sound that would make Tom Holman cry, I'll take it.
3. My room is only about 12' x 15' but I'm hoping to use this sub for years and I may move into a larger space, so I'd love it if it could also be good in a larger room, say 20' x 20'
4. My listening is 60% movies, 30% games and 10% music.
5. My current speaker setup is Polk rt800i fronts, cs400i center, fx500 rears. Since these front speakers don't have powered subs built in I'm really looking for a sub that can do most of the heavy lifting at the lower frequencies.
6. Time frame - NOT urgent. I'm willing to browse the bargains for 6 months or more before buying.
7. Need NOT be a current model. Can be a great sub of years past that still sounds great.

Oh, and one more thing that relates to #7 above, my understanding on speakers is that used is just fine. If they don't sound blown, and there is no noticeable cracking or other damage to the drivers, they should be as good as new and last for decades. True? If so, is it also true for subs?

Thanks in advance!

Thanks everybody!

P.S. While I've always like Polk speakers and currently have an all Polk setup, I'm not especially interested in a Polk sub. My impression of them is that they tend to be a bit overpriced for what you get and that they aren't as highly regarded as the rest of Polk's speaker line from back in the day.
(But that info is from a few years ago and may have changed)

Jared, how are your woodworking skills? It sounds like you want a huge, thumping, manly sort of sub, but for $200-400 that is going to be hard to find unless you build it yourself. Of course you can check e-bay, audiogon, and the classifieds right here on this forum and you may get lucky. Other than that, the most bang-for-the-buck will be the eD choices.

Mojomike -
Thanks for the response. Um, sorry if this is a stupid question, but what do you mean by eD choices.

And yes, I have every intention of scouring classifieds and websites hoping for a lucky find. I just need some advice of what to look (or not look) for.

As for my woodworking skills... If I were to whittle a stick there is a fifty fifty chance it would not be suitable for poking myself in the eye with.

No, the DIY option is not for me. But that was something I forgot to mention so I'm glad you brought it up.

eD: http://www.edesignaudio.com/index.php?cPath=2_41
Note that there are two models to choose from at $375.

As far as what to look for in the classifieds, find stuff that looks to be in your general price range and bring it up for discussion here. I promise you will get plenty of opinions.

eD is an internet direct (ID) brand that sells excellent subwoofers for ridiculously low price. eD stands for Elemental Designs.

Here is a followup question - anything wrong with a vintage sub - technology wise?
Regular speakers are all pretty basic but from what little I know of subs there seems to be more technology involved (adjustable crossovers and other bass management things, connection for a single dolby digital sub cable rather than just two speaker wires etc.)
So, anything I should make sure an old sub has, or reasons to avoid them?

I found someone selling a Velodyne 18" for a good price. He said original retail was over $3,000. Model is OLD-18-8 and I couldn't find anything about it online.

Possibly tuning frequency. If you're looking at something super super old, current movies just might have info they wouldn't reproduce.

That's about it.

I found someone selling a Velodyne 18" for a good price. He said original retail was over $3,000. Model is OLD-18-8 and I couldn't find anything about it online.

it's so old, it's model name is OLD-18-8? :)

perhaps it's a ULD-18
http://www.velodyne.com/products/manuals/63-ULD1518.pdf

Are you sure that Velodyne isn't a ULD-18? I've never heard of an OLD. If it is a ULD-18, that was a very good performer for it's day, but can be out-performed by a new modern $600 sub backed by a full warrantee. The thing is that subs have probably improved more over the past 3 or 4 years than regular speakers have. The internet brands have really brought high value subs to the market that can blow away premium subs from just a few years ago.

Are you sure that Velodyne isn't a ULD-18? I've never heard of an OLD. If it is a ULD-18, that was a very good performer for it's day, but can be out-performed by a new modern $600 sub backed by a full warrantee. The thing is that subs have probably improved more over the past 3 or 4 years than regular speakers have. The internet brands have really brought high value subs to the market that can blow away premium subs from just a few years ago.

yup. the NEW-18 will most likely trounce the OLD-18 :D

Even the NEW-18 is trounceable.:D

Yeah, I suspected that it was the ULD, but when I emailed the guy to confirm he said it's the OLD. I think he's wrong, but then again, maybe it really is that old!

Mojomike - thanks for your input about recent sub technology. That's exactly the type of thing I needed to know.

And ransac, thanks for the link. I'll check that out.

Wow, you guys are fast! I just posted about this a couple of hours ago and look how much I've got to go on now!

I deleted the post because the review was actually on the F-1800R (the replacement of the ULD-18). Sorry. HERE (http://www.hometheaterhifi.com/volume_3_3/v3n3l.html)is the link anyway.

It's pretty interesting reading that old review. A friend of mine has that same sub "F-1800R" from when it was new. It was one of the best subs in it's day and probably still has very good SQ. Note the "large excursion" referred to (Xmax = + or - 13mm). Right there is an example of how subs have changed. There are many subs with double or nearly triple that excursion nowadays. Then, a sealed sub with 600 watts was a powerhouse. Compare that with a Fathom. For that matter, compare that with an eD A7s-450 with 1300 watts.

It's pretty interesting reading that old review. A friend of mine has that same sub "F-1800R" from when it was new. It was one of the best subs in it's day and probably still has very good SQ. Note the "large excursion" referred to (Xmax = + or - 13mm). Right there is an example of how subs have changed. There are many subs with double or nearly triple that excursion nowadays. Then, a sealed sub with 600 watts was a powerhouse. Compare that with a Fathom. For that matter, compare that with an eD A7s-450 with 1300 watts.+-13mm is 2" with an 18" driver. Not too shabby. You see the FSR model was upped to 1250 watts. The FR chart is very good, down to 10Hz, even for today. Also note, he tested HT with LaserDisc.:)

Didn't know JJ has been doing this for so long.

My worry about a sub this old would be that the paper orsurround is dried out and soon to fail.

The seller emailed me to tell me that he doesn't have the manual anymore, but he thinks the sub was made in 1991.
I've got nothing against vintage AV gear (and speakers last longer than most of our HT stuff) but that's a bit too long in the tooth for me.
Question:
When is $500 for a sub that was bought for over $3,000 not such a bargain?
Answer:
When it has been in use since I was in High School.

He is also selling a pair of 10,000 front speakers for 2,300. Those seem like a more interesting buy. If I were a two channel guy. And if they weren't way out of my price range.

Followup - here is what I've decided to do:

I've changed my mind about buying a used sub at a "bargain" price. As I said earlier, I knew very little about subs. Now I know a bit more. And it seems that, unlike the rest of my speakers, the landscape of subs has changed a lot in recent years. And technology and the rise of internet direct companies has really changed the value paradigm.

So I think I'm now looking at stretching my budget just a bit over $500 and getting something like the AV123 MFW-15. I had also thought about the ED A5-350, or even the ED A7S-450, but it seems like the MFW-15 would get me comparable (or some might argue better) performance for less money. (craigsub list)

Thanks to everyone for their input.
I should have suspected that asking advice here would somehow result in me spending more money than I intended... and somehow being happy to do it.

P.S. Thanks to this forum I have also decided to get an Auralex Gramma / Subdude. I'm getting that now to put under my old sub while I wait for the MFW-15. Given that I have hardwood floors and have downstairs neighbors, I'm hoping that it will cut down on complaints.

0h, one last question - my only concern about the MFW-15 compared to the others is that it is only 350w. Should I care too much about that?
Maybe I should go over to the MWF-15 thread to check on that. I'm just wary of wading through another looooong multipage thread. Oh well, it's not like I should be working right now or anything...