Cricket Wireless, which is owned by Leap Wireless, has become the first pre-paid US carrier to offer the iPhone. The company is offering contract-free, "unlimited" voice, text and data for US$55 per month. Note that Cricket defines "unlimited" as a "fair usage" policy of 2.3 GB per month.
As for up-front cost, Cricket will sell the iPhone 4S for $499.99 (16 GB) and the iPhone 4 for $399.99 (8 GB). You can make a purchase online or at one of 60 US Cricket Wireless retail stores as of June 22.