Apple’s push into the US prepaid market has been given another significant boost after Sprint-owned Virgin Mobile announced that it will become the second such operator to offer the iPhone to its customers.

Virgin Mobile USA will offer the iPhone 4 and iPhone 4S with unlimited data and messaging plans through Sprint’s Beyond Talk plans, starting at $30, and will be available on three separate tariffs. The iPhone 4S (16GB) will cost $649 and iPhone 4 (8GB) will sell for $549.

Earlier this week we reported that Virgin Mobile was lining up a move but launch dates and pricing were unavailable at the time. The proposed move signalled a shift in Apple’s plan to dominate the smartphone market as it had done with its iPod range of music players.

Leap Wireless brand Cricket was the first carrier to get a prepaid edition of the iPhone and it did so at a ‘modest’ subsidization rate. This allowed it to offer the iPhone 4 and 4S at $150 cheaper than the unlocked flavors from Apple. The cooperative subsidy isn’t something that Apple needs to do, as it already has carriers banging on its door wanting to carry the iPhone.

Now Sprint, who has committed to purchasing some $15.5 billion worth of iPhones, is now the second to be offering a prepaid edition of the iPhone, having begun selling the iPhone 4S from October 2011.

Why is Apple allowing carriers to offer the iPhone at lower rates? TNW’s Matt Panzarino writes:

By this time next year, the iPhone 4 will be almost 3 years old. It will be using parts and an industrial design that Apple has had 3 years to perfect and make cheaper to produce. If the rumors are right about the screen in the new iPhone just being taller, rather than a different aspect ratio, it will also be using panels cut from the same cloth as the ‘next iPhone’. It will be even cheaper for Apple to make than it already is and easier for it to offer aggressive pricing to pre-paid MVNOs and other carriers.

Virgin Mobile has pushed live a sign-up page for the iPhone 4S on its website, detailing the three individual prepaid plans:

rate chart 520x188 Confirmed: Sprints Virgin Mobile second US carrier to offer prepaid iPhone; from June 29, plans start at $30

The plans come in lower than Cricket’s $55 unlimited plan if customers sign up to one of the company’s Beyond Talk plans and choose to pay auto-pay by Credit, Debit or PayPal.

 [Image Credit: D@LY3D]