Earlier in the month Virgin Mobile let it be known that they would soon offer the iPhone on prepaid, and true to they word, Virgin Mobile has now started to offer both the iPhone 4 and iPhone 4S off contract with an affordable 35-bucks a month unlimited data plan, but of course that does mean you have to part with cash up front.

According to the guys over at Slash Gear, Virgin Mobile USA is offering the 8GB iPhone 4 at a cost of $549.99, whilst if you wish to opt for a 16GB iPhone 4S the price tag is $649.99.

Virgin Mobile now joins Cricket Wireless in offering the iOS smartphone on prepaid plans, whilst Cricket offers the iPhone 4S for slightly cheaper at $499.99, they do charge a higher monthly tariff plan at $55 per month for unlimited data, so it might not work out cheaper in the end.

According to the guys, although Virgin Media claim to offer unlimited data, in reality once you reach 2.5GB you’ll notice some throttling, however apparently the deal does run cheaper than both AT&T and Verizon as long as you are prepared to hand over that upfront cash.

Having said that, whether one would opt to purchase the iPhone 4S as a prepaid smartphone at this stage in the game could be the question, especially as word has it that Apple will be delivering the iPhone 5 later in the year, so would it be wise to hand over your cash up front or simply wait until the next iPhone arrives?