Is he one of those rare breed, responsible 15yo's or is he a regular egg headed twit of a 15 yo?
I only ask because those 3-4 hundred dollar China made QMB 139's are everywhere on Craigs list, and it is the same engine. A shipped Agility can double or triple the cost.
Will he go dirt biking? At 15, I would have killed a plastic scooter in a few days.