Look on Discount Cruises, Last Minute Cruises, Cruise, Cruise Line, Cruise Vacation
You can search for cruises by date, departure port, cruise line, etc. If you look at ships that call a certian port home you can see when the cheaper rates are. ANd they even advertise Disney cruises.
Booking far out (11-12 months) many times will get you the best deal until there are cabins open under 60-90 days out. And if you can wait for 30 days out even better.