We had an unfulfillable mania to complete our collection (which we now know is was VERY difficult/expensive due those 1-2-5 cards that were super rare). Supporting the developers with a couple of dollars didn't hurt anyone. As long as the kids won't try to "complete the collection of all hats). That would teach them to control their spending, understand that they can't just 'buy what they see' (as some young adults get to do on their first paychecks), and chores-chores-chores!