What's a good estimate of what a used PS3 used will go for on eBay or Gamestop after the release of the PS4 I know the PS2's are about $50 now could we ever see the PS3's going for that price?
I wouldn't expect a great price drop. As the PS4 won't have backwards compatibility, there's no reason for the used price to go down before the official new prices do.
don't expect mirracles.