Get the young fella to earn a few dollars for kits. Ask his guardian (mom) what he can do to help around the house. If old enough get him helping you maintain the yard. This will help him realize the value of money and gain confidence, experience and work ethic. Stuff they don`t or can`t teach in school yet needed in life.
Contest vendor tables.
Tell the seller who the kit(s) are for. Vintage kits with poor molds (detail and accuracy) don`t sell for much anyway so maybe you can strike a deal for the swap table queens.
Clean out your hobby room or tool box and I am sure there are some extra tools the young modeler needs. I just reorganized my portable model bench and found lots that is useful but did not make the A list, thus was stored `just in case` I set up a room and keep the portable tool set.
If you belong to a club ask them if they have some dusty kits to sell. Once again the story will help muster emotion and compassion helping out a new model builder. Besides our hobby needs young people to take it up!