That isn't what I said. If a few can't go, then the school should make it happen by having PTO help pay, selling cupcakes, or doing something. 3 students at $10/each=$30. That isn't hard to do even at a poor school. If there are lots of students who can't afford to go or lots of parents are refusing to pay, then I would rethink going on the field trip. I wouldn't leave a group of students behind just because they couldn't pay.