If you were okay with the expectation TMobile's network, Ting would be a good option for you as they use Sprint's network. Port your own Sprint phone and same on your monthly charges. No surprise fees, no cancellation fees/early termination fees, pay for what you use, etc. . . My wife and I are on a data/text plan, which though not unlimited, fits our needs perfectly well, each of us with iPhone 5, and we are paying $45/mo.

There are drawbacks, of course, such as finding your own phone and often the latest/greatest will take some time before they are available/supported, but we have been pleasantly surprised.