I was recently thinking about this, and came up with an idea.
Have the person your selling them to sign something that agrees to pay the specific amount, and also have him send you a photo copy of his/her drivers license. This could be a scanned copy over the internet, faxed, etc. Then send the tickets. If you don't receive the money by game day, then tell the person before hand that you will report the tickets stolen, and the cops would be able to go see who is in the seats, make an arrest, etc. You will have the persons name, address, etc so you could always file a police report. I know it's not fool proof, but for the honest person it would work fine.
Go ahead, tell me about all the holes in my idea.