Sausalito in Marin County has several colonies of floating homes - most have been converted to concrete based barges with houses on 'em. Most of 'em are fairly small, but only a really decrepit one will be cheap. Nice location though, some of them. And they are supposed to be great communities. Marin also has two "Boardwalk" communities where the homes are built on a tidal flat - with a foundation that basically floats on the mud - at high tide the water is under the houses similar to a stilt house, but not every high tide every year - and they all like to a group parking lot by a 5 or 6' wide boardwalk. There are some smaller houses out on these places - and several of those are real craftsmans work. But like anything on water, cheap they are not - and boy, talk about inconvenient - I had a friend lived at the Larkspur Boardwalk, next to last house. He was about 1/3rd of a mile from his car - and everything had to be hauled out there by hand or in a cart - you could ride a bike on it. It was a cool place until a Great High Tide came up thru the floor heating vents and soaked the house in 3" of water.