Republic Wireless offers a variety of super-cheap calling and data plans thanks to its WiFi-cellular hybrid calling setup. In just a few days you'll be able to pair the reasonably priced Moto E with those plans. Republic will start selling the Moto E for $99 on October 15th.
There are no contracts on Republic Wireless, so that $99 price isn't subsidized at all. It's not much cheaper than the Moto E usually is, but you can't just bring any device to Republic.