Buying or selling?
Buying yes, as long as you don't go over the amount uploaded to the card.
Selling no, because the card is eBay and Paypal's confirmation that they will be paid their fees (and that refunds to unhappy customers made) when they come due.
A 'real' credit card is also confirmation that the holder is known to a bank and is over 18. Persons under 18 generally can't enter contracts and eBay is all about contracts.
