Go for the BeBook you can find the website here: http://mybebook.com/
I have the BeBook One for almost three years now and it is perfect.
I replaced the battery with a Nokia one about a year ago.
You can use an SD card for extra storage and you can drag any eBooks (or music/audiobooks) on to it like a USB stick.
No need to be tied to one website for books.
It's a basic eReader with no bells or whistles.
If you want wifi/video etc then BeBook do have more updated models too