How much is the T-Mobile iPhone?

Update (5/13/12): T-Mobile has raised the price of the iPhone 5. Here's the new prices:

iPhone 5

16GB - $$629 ($99 down and $20 a month for 24 months)
32GB - $729 ($249 down and $20 a month for 24 months)
64GB - $829 ($349 down and $20 a month for 24 months)

T-Mobile is launching the iPhone on April 12th. The carrier has stopped subsidizing phones, meaning customers must pay full price for any device. However, T-Mobile is allowing customers to make monthly payments on top of their monthly service charges. Here is the breakdown of T-Mobile's iPhone prices:

iPhone 4 (8GB) - $468 ($18 down and $18 a month for 24 months)
iPhone 4S (16GB) - $549 ($70 down and $20 a month for 24 months)