The world’s most popular smartphone is now available as a prepaid handset on Virgin Mobile. The 8GB iPhone 4 is being offered for $549, while the newer 16GB Phone 4S costs $649 with no contract.

Today, Virgin Mobile USA announced that it would do away with its currently tiered $20, $40, and $60 prepaid mobile broadband plans and replace them with a prepaid, unlimited, $40 per month offering.