I have a Sprint HTC Hero. I got it 3 months ago. I also have a data family plan or something like that (sorry for my lack of knowledge, i'm only 16). Will I be able to trade in my Hero for the Evo? Or will sprint only give me some money towards buying the evo? And if they give me some money, will i have to buy the Evo at full retail price as if i was buying it without a contract? If so that would suck because full retail price will be like 800 bucks! Thanks!