Use a public library.

Although this story may not resonate with you, it proves the point that when you are not worried about paying for your expenses, you may be uselessly wasting money. Now, I don't mean to imply that buying your own books is wasteful, but how many times to do re-read the same book? For our kids, we re-read the same book over and over, so buying some kids' books makes sense for us, but our kiddos love going to the library to check out new books, explore the games, and spend some time together as a family.
Next time, you are thinking about spending some money on new books, check out a public library. If you are with your kids, lots of libraries have story times too. If you are in the Minneapolis area, I would highly recommend the downtown Minneapolis library for kids. It has a wonderful children's section.
Here's to savings some money and exploring the city libraries.