Is this price reasonable for a 55UNB8500?

that is up to you, if you think it is a good price the pick it up. For me it would have to be dirt cheap for me to buy a floor model that is on all day long every day. that tv is aged a lot more then if it where for the same time as home use. I would push for a warranty of something.

I don't think that is a really good deal. I paid $400 more for a brand new one on sale when they where still available about 4 to 6 weeks ago. I don't really like floor models. They have a lot of miles put on them as well as all kinds of people messing around with them before you even get the product. I would not buy a floor model unless they where almost giving it away and that really does not happen. I would pass on this if I where you. I know it seems tempting to be able to get a hold of a great TV like this that is barely available anymore.

I agree, I personally would not buy a floor model. However, I don't believe there is any determent to the tv, since it is not a plasma and leds are known for its long life.

Keep in mind that the tv did have a big temporary drop in price due to a sale at one point, but then as soon as the sale was over the price sky rocketed back to its normal state. Anyone who jumped in during that drop got an extremely good deal on an amazing tv, but that was definitely not the norm for this tv.

At the end of the day it is your money, but I guess I would try to squeeze as much out of them as possible if I were to pick up a floor model. I would definitely ask for a warranty so it will extend the time for you to change your mind.

I'm not so sure on that. I have a 3 year old lcd that just this year is prone to image retention, it also had vertical white lines in the back ground, almost like its the backlight 'hard to explain you have to see it'. My TV didn't have any of these issues a year ago and now its going down hill. Plus any there are many other things that can ware overtime.

Yes, burn in is possible on LCDs. Look at some old monitors and you see the effect. However, it very difficult to do (takes years) and the tv must have been abused. This tv is not that old, last october 09 release and they would not be running a static image and they would only run high def material on it that fills the whole screen, so I really would find it hard to believe that it would have any burn in like issues.

I once did the math. A set in a store open from 9:30 am to 9 pm, on display for an entire year has accumulated approximately 4500 hrs, usually in "torch" mode. In actuality this amounts to not much worse than a thorough break-in as far as the panel and backlighting go, but I've seen caps failures on some Samsungs during their display period, and a few no-name sets have some really odd problems after this much use.

Estimated "half life" (time for set to lose half it's original brightness) for plasmas these days is 100,000 hrs. For CCFL lcds I've heard 60k, don't know about leds.

If you do purchase the set be sure to find out if it's in "store" mode and learn how to do the reset if necessary--usually buried deep in the owner's manual. Sets in "store mode" will revert to factory default Dynamic settings every 10 minutes or so.