I think your confused on how a storefront agency works, The rate that I got online, direct and through AAA was the same rate. How AAA or any other storefront agency earns their money is through the cruiseline and the commission percentage they have negotiated through HAL. Overheard costs are then paid from the money earned by commissions. That is why many agencies started charging for airline tickets or stopped saleing them altogether because the commissions from airlines were slashed.
I will give you this true life example there are 6 couples going on the Prisendam May 31, 2 couples booked online for an outside gtd. they have be upgraded to cat. e. The couple who booked throught AAA has been upgraded to Cat SS. All couples are Mariners with the same amount of cruises. So, if I'm paying the same rate no matter who I book with, I'm going to the source that could get me upgraded to a balcony!