MetroPCS is owned by T-Mobile, and are even cheaper at $40/month with no contract. You can pick up a cheap WindowsPhone (Nokia Lumia 521) or Android (dozens of throwaway models) from them, as well. Unlimited Talk & Text, and 500mb cell/data (which only slows past that limit - it's never cut off, or levied with penalties)
Make sure you go to a company/corporate store. At the franchised stores, you'll get charged for every service/activity/need you have, including basic things like inserting a SIM card for you.
For a phone that you may only want for emergency use, most department stores like Walmart, Best Buy & Target have prepaid no-contract disposable phones that are very basic. Something like $20 for a basic cellphone, with $10 to start with on your account. Use it up as you go, and top off as needed. If you're looking at internet service, though, this is prolly not the best bet for ya'.