Do you live in Northern IL? Do you live near Glen Ellyn, IL? If so then you might want to check out Book Rescue! Book Rescue collects text books from various sources and then turns around and give them or sells them to others for a low fee. School teachers get the books for FREE! However for Homeshoolers there is a small fee. Please see SCARE's Website for details on the fees for homeschoolers.
What kind of selection is there? I don't know for sure because I have never been there. However seeing this local ABC station's news report I want to go check it out! I'm willing to pay the small yearly fee and text book fee! It seems it would be possible for me to get books for the kids for $50 per year. Assuming that I would be able to truly get all the text books I would need there.
From the video it looks like a homeschooler's paradise!
Don't get me wrong I love using what I'm using, but I also like to save money. Even if I don't buy anything I would like to go and at least check it out in person!