Because some people use a Disney Vacation Account which gives a bonus for money spent from the account. This way, when you pay off your cruise, all the money comes from there and you get your bonus. I also fund my account with discount Disney gift cards I buy from BJs Warehouse or Target at 5% off. When we did it, the price from DCL was exactly the same price quoted from every other place I could find. I don't have AAA any longer, but I used to and I don't recall it being much cheaper, if at all.