Getting chatty on Apple's iconic handset is about to get a whole lot cheaper. Starting tomorrow, Walmart and Straight Talk Wireless—a prepaid MVNO owned by Tracfone—will support both the iPhone 5 and the iPhone 4, offering unlimited talk, text and data for just $45 per month, albeit with a couple of caveats.

The first is a doozy on most prepaid networks: Since you need to BYOD to the network, you'll need to pay for the full price of the phone, and unlocked iPhones cost a lot of money. Walmart and Straight Talk are skirting the age-old problem with a unique financing plan, however. If you buy the phone at Walmart, using a Walmart credit card, the store will let you make interest-free $25 per month payments on the phone rather than paying the entire cost up-front. The duo is offering the 8GB iPhone 4 for $449 and the 16GB iPhone 5 for $649, standard prices for unlocked models of those phones.

That $45 per month plan cost, or $60 per month if you want international minutes, is nothing short of dirt-cheap. Even if you factor in the $25 per month financing for the phone itself on top of that, the $70 per month total is still cheaper than you can pick up an iPhone 4 or 5 on a subsidized two-year plan at the major carriers. Straight Talk doesn't offer 4G LTE capabilities whatsoever, though, and the "unlimited" data is only unlimited in name.

Looking at the network's Terms of Service. Streaming video or excessive data and talk usage is prohibited and Straight Talk can unceremoniously dump you if you buck the system. (GigaOm spent some hands-on time with the service and received warnings if usage exceeded 100MB per day or 2GB per month. ZDNet encountered similar limitations.)

Nevertheless, Walmart and Straight Talk's offer is one of the cheapest ways to get off the ground and running with a new iPhone. If you're looking to pick up an Apple handset and don't mind sticking to the basics, it's a highly affordable and intriguing option. One recommendation: Before you drop $450 or $650 on a new iPhone, make sure Smart Talk supports smartphones in your area. Its smartphone network offers fairly wide coverage, but tends to congregate around major metropolitan areas.