Also, don't forget places like Salvation Army, Goodwill, etc. for cheap books. The selection is hit-or-miss, but sometimes you get lucky. I love our local used book stores, too. Both DS and I can spend hours there; well as long as we're looking for books for him. (Are you done
yet, Momma? Did you find one
yet?)
I actually make book covers using scrap-book paper; still inexpensive but a lot prettier than the brown-bag covers ala high school.