Would gamestop take back my game?

So, I finally got Rock Band 2 and of course I want to export some songs from other RB games, but I don't want to spend so much.
Then I read how you can buy em used export and return them, and they're pretty cheap at GameStop.
ANYWAYS, if I buy a used RB 1 and return like the day after, would they take it back and give me a full refund?
Orr, what happens?
Thanks.

So let me get this straight.
your buying a game and then going to sell it back?
Thats a bad idea.
Instead:
1.)buy it used from game-stop
2.) then sell it on amazon.
Game stop buys games for way way way way to low.
If you sell it on Amazon you will make at least 40% more profit.
If you plan on doing this more often I would recommend getting game fly. ( a NetFlix for games)