I have found and interesting thread on
reddit about The Open Book Project.
It is an open source design of an e-ink reader. At this moment the hardware design is mostly done and you can download and have a 2-sided PCB manufactured from documentation, buy complete set of parts. The author prioritizes cheap and easily obtainable components. The firmware is being developed. The author can run some preliminary software and display text, but that is not the final firmare that is planed.
There is a nice and comprehensive description at the project github page
https://github.com/joeycastillo/The-Open-Book
Please note this not a crowd-funding scheme for a vaporware or an OEM version from big manufacturer with minimally modified firmware.
I tried to look for a thread about this interesting project here on Mobileread but I haven't found anything. So, if this post is redundant, please correct me.