There's a store on Washington rd. behind hooters in the old books a million building called 2nd & Charles, they sell new/used games, books, cds, dvds, blu-ray, vinyl records, comic books, a little bit of everything.
Their game selection ranges from NES to current gen games. Most are usually around the same price as everywhere else, some are way overpriced like they haven't given it a price drop in a long time, but occasionally you can find a decent deal. Plus they sometimes have some of the rarer games since a lot of people don't know about the place to buy it all, not to mention the older nes/genesis/snes games you can find.
You can trade in games/books/movies all kinds of stuff for store credit(or cash, less than credit of course), not sure if they give you a decent amount for trade ins though.