Don't know where you are getting your numbers for the games, but you will probably be getting about $10 to $15 for the games, maybe a bit more if you were to sell the Silent Hill game, and what the heck is RDSC supposed to be? The might pay more than I am thinking, but remember, they are there to make a profit, they won't want to buy games for a certain price that people won't even match what people would be willing to spend on those games used.
Good luck with getting a 360, though I don't see what reasons you could have for going for going for a 360 over a PS3 except the size of the online community that would be costing you even more money if you want access to it for games since Microsoft makes you pay money on top of your current internet service to access it, and an extra $100 if you want your 360 to connect via wifi. PS3 has gotten to the point of being just as inexpensive, has a much lower chance of completely bricking your system, free net access on your games, built in wifi, controllers that don't need battery packs, and most of the same major games the 360 has, but some PS3 only ones to compete with the 360 only games.