This week Walmart sucker-punched the mobile industry when it announced that it would start selling iPhones for a ridiculous deal using Straight Talk, a no-contract carrier: $45 a month for unlimited talk, text, and data. Or you can pay $60 a month to add unlimited international calls to select countries.

That sound you hear is AT&T and Verizon trying to get their wind back.

You'll have to pay the full unsubsidized price for a phone up front — $449 for the iPhone 4 and $649 for the iPhone 5 — but you'll wind up saving a huge chunk of change in the long run. After two years, an iPhone 5 would cost a buyer $1,729 total, while the same plan from AT&T would cost $3,550. That's $1,821 in savings over two years.

But is it really the best deal out there? Frederick E. Allen at Forbes breaks down another, cheaper option for people who don't need to have the iPhone 5. 

Sprint Nextel's Virgin Mobile offers the iPhone 4 for $349.99 ($100 less than Walmart) and the iPhone 4S for $449.99 with a great plan in its own right. You'll get:

1. Unlimited data
2. Unlimited texts
3. Options for voice minutes: 300 a month for $35; 1,200 for $45; or unlimited minutes for $55

If you're not a big talker (sorry Mom), you can get the 300-minute plan and pay just $1,189 over two years. That saves you $340 compared to Walmart's cheapest deal with the iPhone 4. 

Of course, your phone will be a full two generations behind and won't come with high-speed LTE (increasingly the standard). But these no-contract deals are worth taking a hard look at if your contract's almost up and you like having hundreds of extra dollars to line your pockets with.