Put down a deposit to lock in the current rate, if it lowers before final payment date you can have your travel agent rebook at that price.
When my NCL cruise for December went down in price my agent simply called NCL and they added an on board credit for the difference, meaning we didnt even have to rebook.
11 cruises in 2012, 90 nights at sea visiting 15 countries
8 cruises in 2013, 56 nights at sea visiting 7 countries
Next cruise: None scheduled
PM me if you need a cruisemate for any Europe, transatlantic, or Panama Canal cruises
Date, ship, cost pp