I was ready to say 1, but I realized that's false.
Someone once sold me their Xbox and their games (like 7 at most), controllers, HDD, etc. for $75. I had already sold the console to someone for $100 and the leftover games I couldn't sell I traded in. I think I ended up getting like $60 from the trade-ins (5 games and an HDD). I believe I made over $100 from the whole ordeal. Pretty freakin' sweet if you ask me.
I traded in 9 games at one point. I got a total of $71.37
By Gamestop standards, that's... pretty bad I guess. I have no qualms though. Most of them were "junk games" anyway and in the end, Star Ocean: Second Evolution and Dragon's Dogma are now one some of my favorite games of all time.
Bleh! Don't you just hate it when you play online, and you're paired up with a team full of Johnny's against a team full of Davids?