There a some great ideas in this section to get you going. There's a sticky at the top of things from recycled household items so also cheap!
Things like hiding treats in folded up loo roll tubes is simple & effective. Even better if you wrap the treat in some loo roll stuffed in the tube. Makes them work for it a bit and gives them something to chew.
http://www.hamstercentral.com/commun...ster-projects/