When my son was younger, he ran out of ammo so I parked him in front of the reloading bench. As we worked, I showed him all the price stickers on the components and informed him that soon enough he's have to provide his own. The ammo lasted a lot longer after that.

I'm a grand uncle several times over but no grandkids yet. (I didn't get going until well into my 30's.) I'm pretty sure my attitude will be a lot different towards them when they do arrive. Let their folks show them the price tags