All DCL does when you check-in is verify that the card is valid, ie they dont' check for balances. So, even if you can use a pre-paid Visa card, the cards still would have an unlimited amount(I believe it's $500 before a charge is made). So, you would still have the same situation, but when the kids went over their pre-paid limit (which you set on the Visa), you'll find yourself with bills left over and you'll still have to pay. DCL can't check everyone's available credit on a card upon check-in and assign a different value to the cards, hence why they do what they do at all WDW resorts, check for validity and then give a limit before they charge that amount to the card. I know the initial charge is $1, since I saw the temp authorization on my CC when I returned home.