That's why it's always good to book with an agent - let them do all the work for you. If you book directly with the cruise line or an online site, you have to do all the work.
But it's always a good idea to keep your eyes on the prices as they do tend to change all the time, especially right now with all the problems Carnival has had lately.
47 Cruises & Counting! Favorites: Paul Gauguin to Tahiti: Uniworld River Cruises in Europe; any of the Celebrity Solstice-class ships; Holland America for 12-nights in the Baltics & Russia; RCCL for 14-night Greek Isles, Turkey, & Croatia; Holland America for 14-day Alaska cruisetour; 10-night Canada/New England cruise; 21 days in Hawaii including a 7-night NCL cruise; Oceania for 25 days in Asia; & 3 months touring Europe by train. And many days spent in all-inclusive resorts!