Treehugger has an insightful article from a former prefab homebuilder. These guys came on the scene a few years ago thinking that they would remake the world in a more sustainable image and a CGI image a day went up onto sites like Inhabitat of remote, unique-looking one-off homes perched over a frozen lake with nobody around.  The fact that the world can’t live away sustainably if everybody is in a Michigan state park on custom-built “prefab” housing a mile from the next human being didn’t seem to percolate into their ideological framework.   Their tiny, overpriced product only appealed to hipster environmentalist millionaires who wanted to live in the wilderness – a market which did not support the dozens of outfits that sprung up straight out of architecture school.  The only functional green prefab idea that came out of this movement was to use recycled shipping containers rather than 2×4’s in urban port cities, and even then half the buildings are currently made of purpose-built containers which don’t save any resources.
A commenter suggests that the *real money* is in the mobile home market, and the refreshing response goes:

The problem is the fundamental disconnect about costs in that market. When you build with well insulated walls, non-toxic materials and better build quality, the cost goes up. The people who understand the mobile home/trailer park system, where you rent the spot and own the manufactured home, balked at the price. No, they laughed at the price. They thought we were all kidding.  The people who understood how much it cost to build a proper, healthy green trailer didn’t get the model of tenure. There was nowhere for them to put the home because they had no intention of going into a park.