Cricket Wireless (subsidiary of Leap Wireless) has announced the upcoming availability of the US' first prepaid iPhone. The offer will open on Friday, June 22 and gets you Apple's handset contract free for $55 a month.

Naturally, that also means the devices aren't steeply discounted. You'll have to cough up $400 for an iPhone 4 8GB or $500 for an iPhone 4S 16GB -- far more than signing a two-year contract via major providers, but still a tad cheaper than the full retail price offered by AT&T, Verizon and Sprint (currently $550 and $650).

Cricket's prepaid service offers unlimited voice and text, while data is technically unlimited, but speeds are throttled to 56-100Kb/s if you exceed 2.3GB a month. Based on habits claimed by AT&T and others, only a small percentage of smartphone owners approach such levels, so it shouldn't be a concern for most users.

For the typical user, Cricket's service seems like a great value compared to conventional packages which hit $70 to $80 a month -- especially over the long haul. Cricket says subscribers on major carriers can expect to pay $2,775 over the course of two years, whereas its own customers will pay $1,719 during the same period.

There is at least one tradeoff in the way of coverage as Cricket's network is largely limited to major markets. It covers about 90 million Americans with only 60 million in areas supported by the iPhone (you can view a full list of the launch cities here). That could be a problem if you travel a lot or if you're in the sticks like me.