Homeschooling is an excuse for bookaholic* parents to buy more books.
*You know who you are.
I came up with that line after dumping a huge load of books by the cash register at the Book Warehouse near my mother's house. These remainder bookstores are great places to get quality books at 20% - 80% off. Most run around half price. They also carry materials aimed at the school market that you don't see at the remainder tables of regular bookstores.
When I went to get the link I saw they've recently opened an online store. Unfortunately it's an Amazon z-shop, which means credit cards only. I hope they change up so that they can accept checks, like the brick-and-mortar stores do.