There is also the ebookwise-1150. I haven't used one, but I've seen that a lot of people here have liked this model of e-reader and the price is certainly right, I've seen it advertised for $89! I have to say, I'm not sure about the files it supports, however, and it is an older model afaik, so you'd have to check that out it you are interested.
https://wiki.mobileread.com/wiki/EBookwise-1150