We have a terrific library of ebooks right here on mobileread. Scroll up to the blue bar where it says
ebooks and you'll find it. Also Project Gutenberg is a good resource.
I have to agree with you that the Amazon listings, particularly for the classics, are often poorly formatted. I've kind of given up on them, myself. I always check here first. The bestsellers tend to be much better formatted, but anything older can be iffy.