Check out the dollar stores. They have great deals on just about anything non-perishable items, especially paper products, crayons, and other school supplies. Use tupperware, decorated shoeboxes and ziploc bags in lieu of pencil cases and those zippered bags that hold pens and pencils. The costs of getting your kids back to school are never-ending, and one thing most people can count on is shelling out more money for schoolbooks and registration fees. You would think that the taxes we spend on practically everything we do and own would cover these costs, but they don't.
Public education is still a bargain, but it's no longer truly free.
Check out local programs in your area. You can get grants to cover book and registration fees if you meet your school district's guidelines. Contact your school district and ask about grants for book fees, registration fees, and the reduced lunch program. A neighbor of mine was surprised to find out that she qualified for all three of these things, although she makes decent money. If you have a disabled child, you may also be eligible for special services and grants that you may not be aware of.