Can someone tell me what the upgrade cost for an iphone is? (ATT)  

It varies on your contract tearms. Depending on weather or not you're in good standing. It may drop the cost in half, but they will try to get you to up your price plan and renrool in a data plan. In the end they will find ways to make the cost not worth it. If you really want to save some cash, wait until your contract ends.

it will probaly cost you around $300.00 or so, but to be sure yu should just call at&t and ask them, you can also aske them if they have any promotions goin on with the iphone, as far as assecories or getting locked into a cheaper plan. sometimes these companies wont tell you these things because the dont want to loose out on money, but my experince with dealing with sprint and tmobile then tend to be nie when you threaten to take your busniess elsewhere. and if that dont work, or you dont want to wait. you can try ebay i have bought from them countless of times and never hd any problems at all. you can also try craigslist.com and just click on you state ten city then look on the list for things for sale and click cellpones. good luck i hope this was helpful.

What?? U sold ur iPhone for Blackberry? Uhhhm, that was wrong decision had made on u..but, i dont know much is it since i do not live in US or Canada or any countries which is provided by ATT.