Libraries don't have to cost a lot of money.
Here are some tips:
1) Renew your books online. When your deadline is approaching, go online using your library card, and hit "renew" for all your books. It buys you some time.
2) If your books are overdue, renew them online anyway. It stops the bleeding until you can get to the library.
3) Use your child's card. Library fines are a lot cheaper for children than adults. So take out materials on a child's card whenever possible.
4) Have a separate basket for library books. Our son's is at the foot of his bed. Library books automatically go in there, so we're never scrambling to find them amongst his other books.
5) Post the due-date tape near the front door. The library gives you a printout with your due dates. Hang it where you'll see it often.
You did get your child a library card, didn't you? If not, take him to the library and help him get his own card. When he checks out his first book, I guarantee you a parenting moment you'll never forget.