I am a liveaboard. I work in downtown Seattle, and live a walk + ferry ride away from the city (this means no car commute). My share of "rent" expenses for my 33 ft powerboat that I split with my girlfriend is $300. I fell in love with the liveaboard lifestyle, partially due to it's bare bones existence. This simplistic living was something I was shaping my life around before MMM entered my life, but now it serves a very excellent job in keeping my expenses down. There is no room to store anything on a boat. Once you have your supplies inside, you have to throw something out to buy something new. This philosophy really forces you to reevaluate your possessions due to your now need to store them. Another area that you cut out is electricity expenses. Before I lived aboard I had a heavy gaming computer with two monitors that were on close to 75% of the time. Now I can't use more than 30 amps at any given time (including my fridge, dehumidifiers, and heaters).
My expenses are about $1300 a month, which is the price for a bare bones studio apartment on the outskirts of Seattle. My boat cost 25k (which is the equivalent price of living in a car). My hobbies have changed since living aboard, but fishing and crabbing have more then paid for themselves in equipment after a season or two (This year we ate around 60 crab and at least 30 trout).
There are some downsides though... It's cold. Especially in the winter mornings. Keeping the entire boat above 50 degrees happens almost automatically, but anything above that requires some sort of heating. Also you have two weekly (or monthly depending on your tank size) chores. You have to empty your waste tanks, and fill your water tanks. If you can deal with them though, few things seem much different then the summer I spent in a cramped studio apartment. (Except we've seen 4 couples taking wedding pictures with our marina in the background. All that was in the background of my apartment building were two construction sites).