No doubt there are some who can cruise on a shoe-string. The more important questions are, what is the minimum amount of comfort you and your crew can tolerate, and for how long?
A good budget should include a kitty for unforseen events. Besides higher than usual entertainment expenses, there should be funds set aside for an emergency trip back home, regardless of where you are. In addition, there should be cash on hand in case the boat needs immediate repairs, again - regardless of where you are.
When you factor these (less likely, but) costly expenses into the overall cruising budget it can quickly grow to a figure that easily exceed one''s net monthly income. Bottom line - have your cruising budget reviewed by knowledgeable, experienced cruisers. It''s always better to prepare and budget for the worst, and hope for the best. Doing it the other way is pretty much a guarantee that the cruise will end prematurely or worse. :^(
~ Happy sails to you ~ _/) ~