There are a couple of different kinds of prefab and each has advantages and disadvantages. One method, modular, (as seen in the Glidehouse) has as much of the work as possible done in the factory but then requires shipping big boxes on special trailers with expensive escorts. Other panellized or precut methods (like Empyrian's Dwell Homes) require a lot of site work, including plumbing, wiring and kitchen and bath installation. Australian designer Alan Gordon has come up with an interesting mix of the two.
His idea is to take the hard and expensive stuff and put it into a Utility Module with the kitchen, bath and services, including all plumbing and wiring. It's design is fixed; everything else is variable and designed to suit individual site conditions and requirements, and supplied in precut and drilled structural components. "Construction to lock-up stage takes just 2-3 days and can be completed by semi-skilled workers. Plumber and electrician are only required on the site for connection and testing. Price depends on purchaser's choice of cladding, lining and joinery, but simple and tasteful starts at around $56,000. Using local or recycled materials can reduce the cost substantially."
Designer Alan Gordon has a "commitment to sustainable design principles - including solar passive design and energy and water efficiency." see more at ::Ecohut thanks, Warren!
Michelle Kaufmann takes a similar approach on a different scale with her ::Breezehouse.