I installed the free Mobipocket reader on my Eee 901 and get my books from the Gutenberg Project. These are old, out of copyright books but there are thousands of them and the cost is zero !

http://www.mobipocket.com/en/DownloadSoft/default.asp?Language=EN

http://www.gutenberg.org/wiki/Main_Page

Until they make a cheap reader and until e-books are easily available at a low price, I'll stick to reserving books at the library for my newer reading material.