We've got a used goods / recycle store in my neighborhood. You can bring anything you want to get rid of that's not worth much, but is too good to just throw away. Many people bring books there. The store sells them for €0.10 per 100 pages. Paperbacks therefore often just cost €0.30. Some that are damaged (tear in the cover, for example) are free.
Sometimes I'd get my books there (before I basically stopped reading Dutch translations), and could have often walked out with 100 books for (much) less than €30, assuming I'd accept a rip in a cover or a cracked spine here and there.
Never felt the need to do so. Therefore I also don't see the need to try and get every possible free eBook...