M.B.
How about just using regular poker chips? They are inexpensive, and you could make each color worth different points, or give a different color based on what it was... one color for general behavior, one color for doing chores willingly, etc.
I've not read how to do the poker chip reward system, but if it works... go for it! You can usually get the really cheap ones at walmart for just a couple of bucks.... write on them with a sharpie if you want to "identify" them...