These sorts of projects hide where the real cost of construction is. Land, foundations, electrical, council permits, drainage, plumbing, telco, it all adds up. Building the walls is a minor cost in comparison, and if you're going to make a house you might as well spend a bit more, and get more house per dollar.
it claims it's sustainable, but i don't see these houses lasting more than 50 years. at least with a normal house you can repair it without having to demolish it.