Although these MUJI Houses have been around for a while, it seemed fitting to bring up their series of prefabs (they start at about $150,000). The MUJI homes (so far only built in Japan) are based on the idea of small space and minimal living (like their products). Their rooms feature an open layout, embrace simple functional forms, and aim to be affordable.
Constructing a home takes about 4 months with the option of a Japanese traditional ceremony with a Shinto priest to remove evil spirits from the land, etc.
You can see all the homes they've built ontheir blog but careful, it's in Japanese. You can also download pdfs of the plans for the different homes.
How long until MUJI and Ikea collectively bring prefabs to mainstream America?