I just picked one of the Boost prepaid Moto E phones for $29, and I'm really impressed.
I enjoy geeky projects, and the setup took a few hours.
1. Load Android studio for fastboot tools.
2. Get unlock code from Motorola for bootloader.
3. Root device.
4. Load TWRP.
5. Install latest Cyanogenmod 13 nightly build.
6. Add an extra 64Gb microSD card as adoptable storage.
Not only was this an educational and entertaining project, now I have an amazingly functional smartphone. I plan on using it as a wifi tablet, camera, and emergency 911 phone. I probably won't be using Boost.
The device is pretty chunky. In fact, I knocked it off the table when it was charging, and I was more worried about the hardwood floor than the phone.
The battery life in airplane mode with wifi on is fantastic (looks like three to four days of regular use on a single charge).
Highly recommended for a tech project and wifi device.