Ya know I think I had heard this awhile back, but kinda forgot about it. I was digging around on Amazon in the kindle section (Kindles Forever!) and ran across free books for the kindle. Now these won't be anything reeeally current. In fact your great grandma and her grandma probably read some of these when they first came out. And they had to pay for them too! But you can get them absolutely free.
Amazon has gathered together almost 2 million pre-1923 out of copyright books. Everything from Dracula to Pride and Prejudice. They also have links to web resources like Internet Archive www.archive.org
which is non-profit dedicated to offering permanent access to historical collections that exist in digital format. Most of these books are scanned copies of physical books so quality of reading can vary. But think of it! Books for free! To get going, you can simply go to Amazon and type: "free book collection" and that should get you rolling. And for those of you without a kindle, Internet Archive has multiple file forms for most books, including PDF, ePub or Mobi