Oh, that's smart!

When one of my sons wanted to have a lemonade stand, i told him, "Too messy and not enough people will stop." Instead, I told him to sell canned Cokes. He would go to 7-11, buy a box of cold Cokes, then sit on the corner and sell them. Sometimes he'd sell two or three boxes in a a couple of hours. People are leery of homeade lemonade but are often quite eager to have a coke, and even at a markup, they were getting the cans cheaper than they'd get a fountain drink at a drive-thru. He would vary the types of drinks, of course, but Coke always sold the best.

He did that for a couple of summers, whenever he wanted money.

So buy something they would want but might not be convenient for them to get right then, and mark it up for charity. Excellent idea, Mimi!