I used a prepaid Visa to buy a gift card from Raise, but was denied at Cardpool and GiftCardZen. Cardpool even held the temporary charge for a few days, rending the card unusable in that time.
I know others accept Amex as a method of payment whereas other only accept Visa and MC.
It would be helpful to see "methods of payment" incorporated into "Markets" tab listing all the different ways one can purchase GCs from each reseller.
Edit: I was successful using a prepaid Visa at CardCash via Paypal.