Weeks ago we went to the circus and everything there cost money. We told the kids don't even ask, because it cost money and we didn't bring any.
When we went on Josh's field trip, I told Josh that we were heading toward the pony rides and he was going to ride one this time. He asked, " Mom, did you bring money this time?". Nope kid you just got lucky!
Side note, I never knew how expensive it was for my kids to be in school. You buy supplies, then give extra money for more stuff, then you have to buy the class t-shirt, then you pay for the field trip and it's just the end of October! I got keep track so I can earn a little extra for next year. Education is expensive and were in public school!