Of course, the list should be simple in grade school and get more complicated as your children get older. I started with Cheese Doodles and other chip-like foods. My kids loved them. I refused to buy them. But they were available in the school lunchroom. So I told them if they wanted them, they could buy them from their own money. Slowly, I added onto the list: candy from the newsstand next to the diner where we sometimes ate lunch, the first trip to the ice cream man each week would be on me but after that on them. As they got older: baseball cards, Webkins (is anyone as tired of these as I am?), admission to the movies or the ice skating rink, presents for their siblings and parents.
Just for fun, put yourself in your child's place. Do you remember how much allowance you received growing up? Compare what you made back then to what you would make now.