You can pay online with your cc. We always do the check-in the day before and pay for our checked luggage at that time. Disney resorts provide airline check-in service. We paid for our luggage over the phone and got a confirmation number, then told the Disney CM at the airline check-in desk. He printed out our boarding passes and tagged our luggage. Disney will transport your luggage to the airport, even if you aren't using DME. It's a nice service.