The owners designed the home themselves and built it for about six thousand UK pounds, an amazingly low price for a house of any size. The home is set into a gentle hill for insulation and to give the "hobbit-hole" appearance. Structural framing is from sustainably-harvested tree limbs from the local area, and insulation is from straw bales and similar materials. The home does have a few modern conveniences, including solar panels for lights and electronics.
The owners have posted the plans and a photo album of the house and site, and the plans are released for public noncommercial use under the Creative Commons License.
Thanks to Lady AElfwynn, who posted this link to the SCA Newcomers email list.