Check out The Voyagers Handbook. the author breaks everything down based on three different "cruising styles", simple, moderate, and luxury. When you are reading it be dynamic, don't put yourself in just one category. Know how you spend and realize that you may spend more or less in certain categories. Its a great book, not like the usual reference book. Also, the newest edition is 2006 I think, so the costs and pricing scales are fairly up to date.