At the sub $60 there is a difference in 2m component cables.
At the sub $30 there is difference in 1m S-video cables.
At the sub 25' there is no difference in optical cables.
I have yet to hear a difference in any digi-coax cables. I even use a radio shack gold video cable for one.
There is no difference in quality RG-6 except in terminations.
At least that is my findings from the cables that I own.
To mix things up I try and have a little of everything.
I prefer the belden/canare industrial style of cable for my setups and this is somewhat cheaper than monster's mas market stuff. (the line higher than the standard but below their fancy line.)
However if I can find overstock or liquidation of somthing prettier for much less I usually go with that.
With digital cables (DVI HDMI optical coaxial) there is no difference (at short lengths) just pick the style/construction you like at the length you want and shop for the cheapest you can find. For this purpose I feel the belden/canare is a bit of overkill as you are bringing a gun to a knife fight. Plain jane wal-mart RCA/Phillips or radio shack will work. but if you have diamond studded interconnects, I can understand wanting something flashier to keep up the looks, especially when you mount your equipment on mirrors like they do at the car shows.
Still I'd reccomend acoustic research for this as they have the best bang for the buck. It's got the monster look and build but not the monster price.
For component I prefer the canare/belden. I have used radio shack, phillips, RCA, monster, and believe that while more expensive than the rest you are buying more cable. This is my 'splurge' cables.
For sub cables I've tried monster, audioquest, NXG, radio shack, acoustic research, and have had good success with all. It's simply finding a length that you need at the price you want.
For S-video it's more complex. Here the termination plug plays the most important role as it is what connects to your devices and connects to the cables inside. If the solder breaks or the conncetor sits loose you will have a bad signal regardless of the cable itself.
I have gone through the most S-video cables and find that the more you pay the more you really get. But in all honesty for a 6 foot length you should never pay more tha $30 for the cable. $50 if you are buying in a retail store.
In the end:
with digital anything - as long as quality, no variation in brand or style
with subwoofer - very slight variation but depends on length and noise.
stereo interconnects - don't use.
component cables - mild variation which can be deemed negligible, however more dependent on quality of dvd player. If you have a crap DVD player your cables won't show the slight edge, but if you have a high end one, you will notice differences, especially at the extremes (lights and shadows) and colorfastness.
s-video - most variation. don't skimp here and make sure the connections are good. It's my experience that it's cheaper to get a good component cable than an s-video, and besides with all compnent in your setup you can use your AVR for video swithing.
speaker cables - not going there.
P.S. If you want to know what I use,
I have bluejeans for all my component cables. different models depending on length and connector though. These are my most expensive at $50 each set.
NXG and monster and AR sub cables. (nothing more tha $25 and I have a 30' length)
NXG, AR master series (my personal favorite consumer cable) and radio shack optical cables. (nothing more than $10 all for 2m and under)
Canare SACD 5 channel interconnects.
Digital Coax - AR pro at under $20.
S-video - AR, radio shack, monster M, Monster consumer, audioquest, all under $35. Slowly I'm phasing out as my two setups go HD.
from the installer RG-6, but after the wall plate, AR pro and master, and belden. This is of course at the 3' length. the stuff from the installer was free (included in the install) and the shorter lengths were $12 and under.
I could never imagine what the MSRP cost of all these cables are. I mean, the 2m AR master optical is like a $100 cable. The monster S-video is like $60. The canare SACD is $100+ But I can't see myself doing that.
Remember, unless you have extreme equipment, the mild differences won't be noticeable. As in you have an old zenith tube and some rca dvd player. No reason getting $50 component cables.
When you have a $200+ dvd player and a ~$2k display then you should move up.