I also had a 360 that had disk tray issues. I was very lucky they didn't check it. I'd imagine it's a YMMV situation. As for the PS3, you can probably get a lot more than $100 if it plays ps2 games, only if you sell it on your own.
Traded in PS3 Slim 120gb with some old games and got $113 (This was at Chino,Ca BB btw). Just incase people were wondering, I tried to trade it in without controller and they werent having it, so I had to let it go. Hopefully they don't shut down this deal, I wanna take in my old/extra 360...