The honest and open discussion about actually cruising costs is refreshing. I too have been frustrated with the "it depends" response and I've been (slowly) working on collecting actual data from various cruising blogs (especially families) as there is far too much anecdotal evidence and built-in assumptions. Perhaps we could collectively put together and share spreadsheets with collected/contributed data via Google Docs or similar.
One big issue I've noticed is separation of true living expenses and amortization of big costs. For example, suppose someone choose to spend 15k for a piece of equipment to upgrade the boat. Totally skews the yearly outlay. Was it necessary? Just for comfort? Was it unique to the boat or preparation (e.g. could one pay more up front for the boat and not have to put that money out as part of yearly costs).
Also, some costs don't scale with the number of people so it doesn't matter if its a solo sailor or a family of 10. Others are directly correlated to people so it matters if its just a couple vs a family.
Settling on a set of categories might be helpful too. Is beer food? Fuel?
or does it deserve its own category?
Thanks to everyone who is contributing real experiences and data with cruising costs. Makes the dream of cruising seem possible and helps others develop plans.