From what I understand, you don't actually put money on a Magic Band. The bands are connected to your resort stay and are tied to a card that is on file during your stay. You can set spending limits, but you don't add any money to the bands themselves. The purchases that you make during your stay are itemized and charged to the card on file. It would seem that, without a card, the magic band would not be able to function as a means of purchasing anything.