Priceline for airfare to join a cruise...... Unless I was flying in a MINIMUM of 1 day early and staying 1 day after the cruise..... Princeline would not be a good suggestion.
That being said..... Many times priceline rates for air will not be too much lower regarding bids accepted than what the current prices are running at each airlines websites.
Spring Break is the culprit here along with rising airfare costs.....
Perhaps try flying out of a nearby airport from your home or another airport in Fla. would help find some lower fares or try to fly in 2 + days earlier than the cruise and the same on the return.
I would suggest using www.kayak.com
as a tool for research that allows you to check 1 - 3 days before and after cruise and alternate airports for flights.
FWIW.... I have used priceline for air when I did not have to be anywhere at a specific time, but in the end, the savings were not that great or worth it IMHO.