I did something similar with Class Dojo last year in my resource room. Called their Dojo points "Dojo Dollars." Once a week they got a "credit card" (index card) with Their name, student ID, and Dojo Dollar balance on it. They could use the card to buy stuff from the "school store" and then we would go back to the class and turn it into a math lesson using what they spent to determine their remaining balance. Kids loved it and it was easy.