I usually get mine from Game Stop (online or at an actual store). The online shop offers deals from time to time, and they have a great selection of used games. The store also has a collection of used and new games, and I have one very close to my house. Otherwise I go on Amazon (online store). They have a pretty decent selection, and it's a very easy site to navigate through their categories or keyword searches. I would love to check out a flea market, if we had one around here. I did in the last place I lived, and it was great for things like PS2 and gameboy games. I'm sure CraigsList probably has some that are decently priced. Goodwill might have some, but there selection is usually pretty terrible.