Never underestimate
Project Gutenberg.
Yes, it is mostly classical literature, but they have branched out immensely and.. always
Free!
Yes, Scribd is a fantastic source for more modern works, and with a simple login, you can download most of what you read in PDF form.
I first found P.G. in about 1990. To date I have some 1,800 books from there, most of which I have converted to HTML myself (a little "pay it forward" present for my grand kids
). I keep about 320 of them
online here.