What this really means is that your budget depends on your tastes, and vice versa. Someone who eats out frequently will spend more than someone who cooks on the boat.
Some people pay for guided excursions and commercial dive trips, others explore on their own.
The boat and equipment you choose is a big factor. Heck, the Pardeys have been doing it for decades. A big boat with a lot of gear will cost more to outfit and maintain and fuel and fix. In the end, I decided to lay it all bare and show every dollar we spent and where it went. We track all our expenditures with Quicken.