The words "cruise" and "budget travel" are rarely used in the same sentence. However, according to the folks at Vacations to Go :

To protect the full-fare business they receive from traditional travel agents, cruise lines will not allow many of the deals you are about to see to be advertised in newspapers or magazines, or on television.

Are you a spontaneous type who is not adverse to planning a last-minute cruise vacation? Register at their site and receive emails about last-minute cruise deals. Registration is free! The site is also highly informative. Check it out!