As mentioned before, there are ways to "get back what you gave" in trade, but before doing that, I would avoid the same mistake by doing some research. As it looks like you have a PC, there are hundreds of places, like this one for example, to make sure a game warrants a purchase. Not sure, always rent first. Nothing drives me crazier than taking one of my nephews to Blockbuster to rent or to a store on B-day/Christmas for them to pick out games. I know going in they'll pick the worst schlock on the shelf and no amount of Uncle Mojo saying "hey, what about ----------?!?!" is going to dissuade them from the crap.
Also, I know spending your parent's money is always easier than spending your own, but when in a situation where you can't buy games much on your own, MAXIMIZE what you have. Unless its a special must-have game, you could likely have bought two games used for the same price. Heck, I'm 36 and Good Wife Willing, can buy a game whenever the mood strikes. But still, I waited for the price drop on Super Smash Brother, plus a sale, and bought SSBM, Eternal Darkness (pre-played) and RE for 48 bones. Thats thrifty free-market stuff, my boy. Parent Manipulation 101 Tip: Talk them into the high priced game, then look puzzled and say: WOW, instead of this, I could get both of these for the same price!