If you've never been to the giant warehouse sale with the books used in the school Scholastic Book Fairs, then you've got to try it. I've been three times a year for over five years. There is usually a beginning of the school year sale, a sale around the holidays and one at the end of the school year. You can register and get a fast pass coupon too. Every time, I think that I won't need that coupon, and every time, I see too many treasures and the coupon comes in handy. You can find books for a dollar, books that have percentages off, bargain bins, and my favorite...buying hardcover, and pop up books for $5.00.
Here is the link if you want to see about a sale in your state. Most of the sales are in the next two weeks. But I'm warning you, you'll come home with a box a books very easily. I have to warn my husband I'm going.