The deal I’ve had with soxboy is that he can charge things he really needs (school supplies, shampoo, etc) to his school account, plus he can charge things from the snack bar as long as I continue to fee that his snack bar expenses are reasonable (i.e. if I start to see that he’s buying food for all his friends, that’s a no go, but if he’s buying the occasional snack between meals because he’s a teenage boy and is hungry all the time, I’m fine with paying for that). But if he wants to buy something that he can’t charge to his school account – i.e., ordering pizza to be delivered, going into the local town for ice cream or a movie – then that comes out of his own money, from summer job savings and birthday gifts. I also let him order things from my Amazon Prime account, as long asks first and we decided who should pay for it (new squash sneakers? I pay. birthday present for his girlfriend? he pays me back). So far it’s worked great, but largely because he’s pretty responsible and trustworthy.