What are the items you put inside a party bag without costing a bomb? I am planning a birthday party for 40 kids in pre school. Appreciate your input.

I will avoid tidbits as a think a lot of parents won't allow their kids to eat and the food will end either in the caregivers stomach or dustbin. Stationary, puzzles, notebooks etc from taobao are not that expensive but for 40pax added up still will cost some money