Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A406 Safari/7534.48.3)
wirelessly posted (mozilla/5.0 (iphone; cpu iphone os 5_0_1 like mac os x) applewebkit/534.46 (khtml, like gecko) version/5.1 mobile/9a406 safari/7534.48.3)
So you won't be starting a new contract, and thus will pay the full, unsubsidized price, correct?
Look at the current prices of the iPhone, and save up that much. It is unlikely Apple will change the price significantly, though there are, of course, no guarantees.