As a kid bootstrapping online funding, I used prepaid debit cards available from many retailers. AFAIK there still isn't any kind of point-of-sale age check, and while some providers who use CC info for age/location verification can filter prepaid cards, VPN providers don't care.
It makes sense. Prepaid cards are not banks and they take very little risk in letting an unverified person get a card, as the card only has the money the person paid for it. They can not overdraft. Adding to that more and more online companies are rejecting said cards, at least the major online stores anyway.
