Check out this wild and wacky website American Science & Surplus. They sell closeouts of things you really don't need. The best features are the hand drawn illustrations and amusing descriptions of each product. Choice Example:
Embarrassing Product #14 Occasionally, very occasionally, we are embarrassed to be offering a product. This is one of those occasions, simply because the item is so trivial. It is a plastic hamster exercise wheel. Yup. A 5-1/2" dia x 3-1/4" thick cage-like wheel. The hub clips to the cage bars on one side while the other side is open. We suppose you will need one if you bought a wheel free cage, and your hamster is pouting as a result. Or you could convert into a lazy susan nut bowl. (Twirl it to bring the Brazil nuts close?) According to the package gerbils will eat it, but we don't recommend buying it for gerbil food. No mystery why this item is available in surplus!!
$1.75 / EACH