I don't believe you are actually allowed to re-sell the game, once it's been opened [if yours hasn't been opened, of course, then disregard this]. Not that they can necessarily track it, of course.
Is the t-shirt the one with the text logo? How's that shirt? Gogamer.com claims to still have that shirt, and ordering from them would be about 4 bucks more than Walmart.com, and include a shirt. I like 'free' [or low cost] shirts.