Probably between $100-$200. I periodically trade games in, so I don't have a lot to sell back. And a lot of my games I do have are either A) games that I loved, but dropped in price quickly so the trade-in value wouldn't be much (Alan Wake, Batman: Arkham Asylum, NBA 2K games of various years), or B) have been out for a while, so price has dropped due to time (Resident Evil 0, 4, and 5).
My biggest profit from any game would probably come from either Dead Space 2 or Marvel vs Capcom 3.