Kimberly, your question re. cruise lines charging so much for single supplements is one that has been asked and talked about for quite some time. I agree it isn't fair, but sometimes travel agents do find good prices without the supplement.
I just always tell people to consider an organized singles cruise with a roommate assigned according to age, smoking or non, early or late riser, etc. The prices for these cruises are always terrific. Check out the Singles Cruise calendar in Cruisemates' Singles section, especially the Cruisemates cruise July 4th sailing from Miami.
In addition, there is a club called J.U.G.S. (Just Us Girls) that finds congenial female traveling companions. Check out my article on that.
Good luck, and if you have more questions, just ask. We're a friendly bunch here on the Singles Message Board...and all over Cruisemates, for that matter.