Another huge library fan here!! I couldn't afford my reading habit if I had to buy it all. As far as fiction, I will only buy my very favorite authors in hardback, but 2 of the 3 have passed on. BOO HOOO!! I have found some cool books in the B&N sale section, though.
Used bookstores and Goodwill. Library discard sales. No, not the latest (but whatever, if there's something I specifically want I'll use Amazon) and LOTS of neat stuff you'd never find otherwise. Of course then the problem arises you have to buy more bookshelves...