It all depends on where you want to cruise
$3000 a month in the UK would be hard. In St Tropez, France
you would need twice that at least just to be called poor!
But in the Islands of the Pacific you could live very well indeed. And in the Indian Ocean
you could live like a king and have all the servants/elephants you want!!
Marina costs vary so much too. From 1,000's of dollars a week in St Tropez to $100 a year for a wharf in Newfoundland