PC World:

Virgin Mobile is the second U.S. carrier to offer prepaid iPhone plans, which could save you more than $500 over the lifetime of the phone compared to the big three carriers. Virgin’s iPhone deals go live from June 29, while Cricket’s prepaid Phone offers start June 22.So how does Virgin Mobile’s deal stack up against AT&T, Verizon and Sprint’s offers if you want to get an iPhone 4S? Since the big three are selling the iPhone with two-year contracts, I calculated the ownership costs of a 16GB iPhone 4S over this period with the lowest-cost plan available in order to compare it with Virgin and Cricket, which do not require a contract, so you’ll pay month by month.