I recently got a cheap Doogee X97 as a backup phone. It was pretty much AOSP except for the launcher and 2 extra apps. I was impressed by the value of the $60 phone. 16 GB flash was too little for me though. I handed it to a friend and got the sturdier, waterproof S51.
No holes in my screen, 5 days of daily use battery and 4GB/64GB + dual SIM + NFC + microSD + headphone jack for $100 is pretty sweet. Also OEM unlock is possible from the dev menu without extra steps. Firmware is available as a zip from their forums.