Hey Man,
There is Already a post for PS3/Xbox games exchanges
here in the Forum,
You should head there and put up your game for trade/sell/exchange or Whatever :)
And just to Give you a heads up,since your New to the forum,
Next time, before posting anything in the forum, try a quick search of the subject and check its availability,
And then post in it, or just open a new topic :)
Cheers man.