Not sure if I like this. I think he's way overdoing it. Two dollars, maybe five would be appropriate, along with a reason like "because you were son friendly and fast". I'm sure they would have been just as happy. They probably don't have a concept of what that much money even means. This just misaligns their perception of how good work should be rewarded. Now these kids are likely to be a little disappointed when someone pays the normal price or even twice that.