Many of the answers written are correct, but what we've found is, that just like living on land, you spend what you've got.
Sounds kinda odd but it's the truth. we've been on the water full time for the past 4 years and have met many people going in all directions, and after awhile the question never comes up, unless you happen to be a new cruiser or wishing to be one. Most everyone works part time here or there to keep the cruising budget full.
As far as money out of our pocket, we've had months where we spent as little as $50.00 but we've had others that we spent $3000.00. Like the month we broke the windless and our ding was stolen.
We spent a mass amount of money to outfit the boat in the first place but the sum of around $600.00 a month is a target we try to stay near.
But you have to understand, we dont drink that much. We only go out to dinner a couple times a month, and I trade a lot while I'm out..
Cruisers really dont have much money, so when you can help someone out in exchange for a meal, you've just added to you,re kitty.
Its like, if you don't spend it, you've earned it.
And its not hard at all... A year or so ago I changed the fuel filters on my motor.. Somehow I got air in the line and could'nt get it out. had another cruiser help me out. The payment was dinner for him, his wife, and two kids... The wife cooked up a big stew and baked a couple loaves of bread and we all sat around stuffing ourselves and watching Capt Ron.
We made some great friends and My motor runs great, and not a penny out of our pockets.... Well maybe a couple for the added stew meat.
My point is, you dont have to be a consumer to be a cruiser.