You can pay for cruises through several of the more popular programs, but the redemption rates are atrocious.

Also, there are a few points earning cards out there - RCCI and NCL spring to mind.

Best thing you could do though, is pay good old cash money (through a portal, using a points earning card) on a consolidator site.

2 things that could help you out here:

1. Tell us where you want to go, on what line, and when.

2. Have a mod kindly move this to the Cruise sub forum.