Stop by your local public library. Most have an expansive assortment of books available to anyone with a library card. If the library doesn't have the book you need, request it from a nearby library via an interlibrary loan system.
Visit a university library, which usually has millions of books. Although you can't check them out unless you either study or work there, you can read and photocopy them while there.
Use Project Gutenberg. It archives thousands of books, and you may download and print them at no cost.
Use Google books. Google Books has archived millions of books. Read entire books with expired copyrights and preview those with live copyrights.