I am going to throw in my 2 cents. I have never found AAA to be cheaper. I have received quotes by calling them numerous times and I have always found better rates.
Same for my sister in law, she went to an AAA office (storefront) and they were higher than what I found for her. I am not talking last minute deals or email only sites.
I don't think any one agency is always the cheapest price. I can get quotes on 2 different cruises and one agency is the lowest for one cruise, but the other agency is lower for the other cruise. Another thing I found was a site had one good price, but after talking to an agent, the price got even better. I found my brother a great price on a popular site and he called them to transfer his cruise booking from the cruise line to the TA. She got him a better price than what was published and also a 2 category upgrade.