Ting.
Ting is a MVNO that uses Sprint's network. Depending on usage, you can have a full featured smartphone starting at $6 / month.
The catch?
First, the phones are not subsidized by the carrier. However unsubsidized phone prices have been falling. A mid-range phone like the LG Optimus Elite can be had for $200, an "older" high-end phone like the Samsung Galaxy S II can be had for $430 or a current gen high-end phone like the Samsung Galaxy S III will set you back $530. Being unsubsidized, that means there are no ETFs. Wanna new phone? Wanna jump ship to a different carrier? Cool. No fees to do that and you can sell the phone to fund your techno-lust.
Second, you are only charged for what you use, so your bill will not be the same month to month, most likely. But that's a good thing. You don't sign up for a traditional plan locked in at XXX minutes, XXX texts and XXX data. You select a starting point for those items, and each month your bill will reflect your usage. If you go "over" on minutes, your minutes are bumped to the next tier. But if your texts are "under" you will be refunded the difference. It is very possible in that scenario that the overage and underage will "cancel" each other out. With moderate usage, I know several people keeping their monthly bill under $20 for a smartphone. Even with heavy usage, your bill will likely be less than you currently pay now. Ting has a savings calculator to help you understand the difference:
https://ting.com/calculator
I have yet to hear a bad thing about customer service from them. Service usually starts with an email, but will transition to a phone call when necessary. And when you call, you always get a native English speaking person on the phone - I believe the call center is Canada. And billing questions / disputes seem to always end in the customer's favor with service credit. One person I know had the first two and a half months paid with service credits before he had to plunk down his own money. All because the phone he wanted was out of stock ($50 credit) and the Android update used data rather than WiFi (another $10 credit).
If you want to have additional phones on the plan, that's only an additional $6 per device. And you share the minutes, texts and data, with the same overage & underage bumps/refunds on single phone plans.
Though Ting only opened for business in February of this year, they are part of Tucows the internet company that's been around nearly 20 years. That means they won't be disappearing in the middle of the night anytime soon.
[-dent-]