Scurvy-yard-dog,
B
We bought our sailboat new in 2006. It is 43 foot long and we have traveled all through the Caribbean and the Bahamas. Our engine now has 1100 hours and burns about 1.5 gal an hour and pushes the boat at 8 -.8.5 on flat water. We could get it down to a gallon an hour or less if we slowed down to 7 - 7.5 knots.
I figure that the boat will cost on average $1000/month, on average. permanent dockage $250/month on the Chesapeake. Insurance, $140/month. Electricity at the dock, $30 - $40 per month. The other $500 or so is money you have to set aside for big things that break.
A gallon of bottom paint can run more than $200/gallon. Our boat takes three gallons every two years. Almost any minor issue will cost you money and not infrequently a boat unit. (boat= break out another thou). So, while I go for months and months without spending the allocated $1000, I have to set money aside so that I have it when I need it.
As far as boat life, you will find that you will spend what you have. I have learned that folks tend to end up with folks who spend similar amounts of money. Some folks go to the bars and restaurants every night, other don't. Some never fix anything on their boat and others polish every screw.
A serviceable set of cruising sells for our boat would cost $6- $10,000, depending on how fancy you get. These sails could last you 15 - 20 years with care. Of course, they will need occasional mending and new sacrificial cloth. Last sacrificial cloth mounted our our boat ran about $600.
Others will have different figures depending on the size and age of their boat. We are looking to move to a trawler because of the room and we are most likely done with bluewater sailing. I expect to burn 5 gals an hour at trawler speed and to spend a bit more on boat maintenance. Just think about servicing two engines every 100 hours or so. We would often go a year and never put 100 hours on the boat, or genset.
Good luck