A previous answer said to try Marcxo Polo, but she does not sail to Carribean.
As far as 2008 is concerned, if you fancy the Eastern Med try The Blue Monarch. Have just returned from a 7 day wonderful cruise aboard this ship with no single supplement during April - June and September - October. During 2008 she will be doing The Golden Fleece itintery ( the one I;ve just done) for £599 with no single supplement, great ship (even although she is getting on a bit, but as we are of similar age, so are we). Also Doing 5 countries 3 Continents in 2008 which I am going to book for May 2008. Food excellant and it is great value for money. The brochure can be downloaded from www.monarch-cruises.com. e.mail www. email@example.com. These cruises can be booked also on www.###.co.uk. If you would like any more info please feel free to contact me at firstname.lastname@example.org. I absolutely refuse to pay exhorbitant single supplements, but really don;t know any cruise lines that sail in the Carribean with no single supplement. Good luck with this one, let me know if you come up with anything.
Try orient lines on the marco polo ship they were advertising no single supplement, i also got a cruise on the norweigian sun [NCL] with only a small supplement it was a great cruise to the carribean. GOODLUC.
Just a suggestion but try "vacationstogo.com" they may help even if it is a cruise only booking. Regards...Falan Dow.
I've just had another thought. Cruise only tickets should reduce the cost if you book your own flight and transfer, and they are offering some really good prices with Costa on this site , about £229, so even if you double that it isn't bad at all. Plus Cunard used to arrange a shared cabin if that rings your bell.....Yours Fala.