I agree with KLD. Unfortunately in most cases you can't get the great sale prices on the accessible cabins (well at lest through on-line sales). This is partially because there are so few of them (accessible cabins) and they don't need to put a sale price on them because they book up quickly, and partially due to the fact that some (preferred) agents can block/hold a chunk of accessible cabins in order to sell a group cruise.
But if you work with an agent who monitors the cruise prices and reprices the fares when they fall, it can save you a few bucks.
Editor, Emerging Horizons
***edited to remove commercial reference***
The only accessible travel magazine.