You cannot use the word cheap and iPhone in the same sentence. You must go to seller's carrier with them to make sure there is no outstanding bill, which would prevent you from activating your phone. Do not buy an iPhone before September 12, when the new one is announced. It will be available in stores September 21. After the 21st, you are better off buying an iPhone4s for $100, with a two-year contract from one of the major carriers. iPhones can have problems. I needed two replacements to get one that worked perfectly. You will have no such protection with a private sale and you won't get a better price than through a major carrier with a contract.