Magnetic spice racks made out of cereal boxes. All you need to buy are the magnets... provided you have boxed cereal, tape, scissors, a ruler, and something to write with on hand! I found 1 inch round magnets at the craft store for $1.69 per six pack. Each rack used six magnets.
You will need the following:
Cereal box, or similar
Magnets (I bought 1 inch round ceramic magnets at the craft store, 6 per pack)