Re: $3000/mo cruising budget
3000 is doable. But its also a dangerous level. Why? Because you have SOME money, and its easy to decide that you have SOME money to spend on an item that could be seen by some as an extravagance, yet you deem it to be a necessity.
We did it when we upgraded our dinghy. The old one was certainly serviceable. It held air and we got around. But as a very old design it was a very wet ride. We got tired of that so we spent $3000 on a new AB RIB. Much nicer ride and we're happy. Necessity or extravagance? Keep up those kind of expenses and the budget can quickly expand to 6000/mo!!
We also keep track of almost every penny we spend so we see how these decisions affect us over time. When we control our urges, we can cruise for months at around $1500 per. But that ain't our annual spend rate!!!
You should be able to calc some fixed monthly numbers to start with:
Health care and health insurance including prescriptions
Cigs or other habits
Dining out based on number of times per week and level of price you're willing to pay
All other fixed monthly spending like netflix, yachtclub, porn paysites, etc
Diesel; how many miles will you travel per year? Easy to run some numbers. If you are coastal cruising, just figure motoring 100% of the time and any sailing time will be a bonus. Honest coastal cruisers will tell you they motor almost all the time or at least motorsail. Offshore is a totally different equation and you'll need to look at replacement costs of the sails instead. Figure new sails and rigging about every ten years as a starting point although that is widely variable.
Dock time: highly variable depending on your level of acceptance with always running to shore in the dink. Also, some places you might want to visit are not easily accessible via anchoring. You can get by with almost zero docktime but will you want to?
Bottom maintenance: Can you dive to clean your bottom periodically? Divers run from $50 to $200 to clean the average 40' boat and you likely need 3 to 4 per year. Then there is the haulout, blocking and painting of the bottom every 2 to 4 years.
I'll repeat the question; where? Big differences in where you plan on cruising.