Sorry if most of you have heard this by now, but for those of you who haven't, Gamestop is going to be giving you a free used game if you buy two used ones in the same transaction. Just think, MontanaHatchet, you can now (sort of) go to town!
A Gamstop employee also posted this trick on Cheap A** Gamer:
"To clarify the Buy 2 Get One Free........
*It is a Buy 2 Games/Accessories Get 1 Free(of equal or lesser value). Used Systems can be accounted for, but must be overridden by the manager on duty. DVDs are NOT included with this offer. They have their own offer of Buy 2 Get 2 Free OR Buy 2 Get 4 Free.
*The computer knows to give the customer the cheapest game for free, but if you purchase 6, 9, or even 12 games it will give you the most highest valued cheapest game for free. If you don't believe me you can ask the employee to ring multiple transactions.
*EDGE card for 10% Off is stackable
*Extra 10% Off Coupon is NOT stackable
*You CAN return any used merchandise within return policy(7 days ago) to re-ring for the Buy 2 Get 1 Free. Keep in mind that this is totally based on the store manager. If he or she is a jerk, try somewhere else(it helps if you're trying to spend money since this is what the purpose is.)
*As mentioned above you could technically buy 1 or 2 games at a location, go to a different GameStop/EB Games, return the 1 or 2 games there, and complete your transaction because you may want to get a game at 2 or more different locations
*Purchases online are refundable at the store and are deemed okay to re-buy for a Buy 2 Get 1 Free.
If anyone employed at GameStop denies you the 7 day return to do a re-purchase for Buy 2 Get 1 Free just try to spend a little money on the transaction and they'll let it go. Being an employee I wouldn't want a guy to come back and return 9 used 360 games, to re-buy them and I'd have to refund him like 150 sum odd dollars. If he spent even a little extra I wouldn't care. If it helps too, if you get a renewal on your card or reserve a game they'll probably do it in a heartbeat. As a tip for you guys, retailers love it when you walk in and say "Hey, can I pre-order...." 
"
So for those of you in the U.S., this is your chance to strike!
Another poster who also worked at Gamestop added this trick:
"If I remember correctly, you can get one of the more expensive games from the 3 as the free game if you purchase 4 (as in, 6 games total (b4g2 free).
If you only get the 3 games, obviously the cheapest one will be free. Add the other 3 games in the same purchase and it should work. My friend (store manager) and myself tried this out during the Black Friday sale last year and it worked.
Take three games up to the counter, have the employee process it, then have him/her ring up the other 3 games and once it's totaled, it usually knocks off one of the expensive games from your second batch as opposed to the cheapest game. I didn't work today, but I will on Thursday. I will try it again to figure it out completely. "
I'm not sure if that actually does work, but you can always ask them to try, right?
And my apologies if you already knew this.
