Oh, by the way, I wouldn't pay the $500 deposit, unless you're rich and don't mind spending $800 for iPhone.
A deposit isn't an extra cost for the phone. It's money you give them that you eventually get back... Either through it being used to pay your first bills, or as a refund later on.
AT&T isn't jacking the price of the phone up an additional $500, unless you choose to cancel the account and run off.