I doubt the moderators of this board will allow an answer to your question since it could be used for advertising by unscrupulous Travel Agents.
What most people usually do is go to any of the online agencies and get pricing to compare. Then when they have settled on a particular cruise and found the best price, then they call their personal TA to see what deal he/she can get for them.
Thomas (who uses for comparison, icruise.com, buycruises.com, mytravelco.com)
I do just what Thomas mentioned and include a land based quote like AAA , Vacation Outlet which is part of the National Leisure Group (Orbitz) or cruisesonly or cruiseone (on line but with local agents). You must feel comfortable with your valuable vacation time and money. A good agent whether on-line or in an office, is priceless when you have a problem or issue. Always check on cancellation policies and fees. Up until 70 days before your cruise, there should be no fees. Make sure the person is responsive. If you don't get a call back within a fair amount of time. Seek other advise.
Thomas is correct. We really couldn't allow that type of question to be answered publically as it does lead to agencies trying to make claims of them being the best etc. Additionally there truthfully is not any one agency that will always be better than anyone else. Depending on the line, the date, the cabin, and everything else you can possibly think of the price may vary from just a small amount to a great deal between agencies and between cruises. It would not be fair to everyone to just name a few. Here is the best suggestions I can give you though. Go to the website of the cruiseline you are wanting to sail on and find out what they are charging for the date and cabin you want. The more detailed the better. That is your base price and you will be looking for something below that, hopefully at least 10% or more. Then check the major travel agencies and searchable websites and see what they are getting for their cabins. That will give you an idea of what they are basically selling for right now. PLace an ad right here on Cruisemates in the Bargain Finders area and allow the TA's the read it to make you an offer. Also check out the local agents near you and the agents that advertise here in the Cruise Bazaar area, we know them to be reliable. After you have accumulated all this data and have sifted through it locate the top three or four in pricing and figure out which one seems to offer YOU the best deal in terms of pricing, service, and ability to communicate with you and who just makes you feel good about them. That is the one you end up choosing for your vacation and then you no longer worry about what 'coulda, shoulda, woulda' been as you know you got a price that YOU are satisfied with.
In addition to Jim's comments above, I'd also add a comment he often uses but said it in a different way on his post. That is; the best deal is not always the best price.
Wouldn't you agree that for $10 more per ticket it would be worth it to have a person in your town who you could look at square in the face for information, advice, etc.? Somebody who has an office you can drive to and converse with? Maybe somebody you can rely upon on future cruises to treat you properly?