As our boat is our home, a business and transportation, I guess I look at it a bit differently than a recreational sailor. Though I've not lived in a house I would assume the costs of maintaining a boat and a home are comparable.
Regular expenses such as utilities, are probably a bit cheaper on the boat; we average just under $200.00, (water/elec/garbage) a month, as are things like fuel for our Zodiac vs a car. Insurance is definitely higher, but taxes are way less, especially considering I can live waterfront in a place like Charleston, SC on a boat worth 250, whereas a home a few hundred yards away is millions.