A:Answer They'll set you up with a contract through AT&T in store. If you have good credit and sign up for the contract, then out of pocket that day you'll just have to pay the taxes due for the phone (around $55 where I am).
If you don't have good credit, you can expect to pay a deposit that's usually refundable after a year of on time payments that I believe is around $250-350 for most people. Then you would have to pay anywhere from $300-400 in store.
If you do the contract, your first bill will be extremely high with added fees (ex: activation fees). So I would plan accordingly. You'll get an email from AT&T a day or two later showing you how much your estimated bill will be. This is nice because it let's you know ahead of time what to expect and also gives you a chance to return the device if you feel you can't afford it (I think it's 14 days to cancel, then you pay a pro-rated around for the service you used).