A friend just sent me a product listing for a really cool gadget. (Thanks, Steve!)
Banggood is now selling an epaper development kit called the M5Paper. It costs $73 and features a 4.7″ E-ink screen powered by a 240MHz CPU with Wifi and Bluetooth. That is a little under-powered for an ereader, but this would still make a great platform for a project to develop your own E-ink controller for whatever project you are working on.
It has expansion ports, a microSD card slot, a 1.15Ah battery, a capacitive touchscreen, and internal connections for things like temperature and moisture sensors.
If you get one, I would love to see what you do with it.