I've only started training recently (no gi) and bought a couple of pairs of Nike compression shorts, but I'm finding that I would probably be better off with full length compression pants, as I keep getting mat-burn on my knees (to the point of bleeding), among other reasons.

The price difference between the ebay ones ($20) compared to Nike ($60) or Skins ($100) is quite substantial to me, especially since I want at least a couple of pairs, but there's no point in me buying them if they are just going to fall apart after one training session. So, are the cheap ones on ebay worth getting, or will I just be throwing my money away?

The brands I'm mainly looking at are "Take Five" and "FDX", though there are plenty of others at a similar price point.

EDIT: Thanks for the replies everyone. I neglected to mention that I'm in Australia, and some of the options suggested may end up being more expensive due to shipping. Considering most people who have tried the cheap brands seem quite happy with them, I think I will buy a couple of different ones to try them out. Cheers.