From the website:
Strategically located in the awesome San Juan mountains of Southwest Colorado, this patented steel-reinforced concrete earth home was built to withstand almost any natural or man-made disaster you can name. It is more secure, safe, and functional than any conventional house could ever be, yet still has a level of comfort that one might not expect to find in an underground home.
The house and its 4.3 acre parcel are currently offered at only $475,000 ($20,000 below appraised value). Or $495,000 for the house with a 4.38 acre boundary adjusted parcel.
The house is also equipped with state-of-the-art air filtration system that can filter out biological and chemical agents, and even radioactive materials.
Can't even buy a decent one-bedroom fixer-upper at that price in Southern California! http://ultimatesecurehome.com/secure_home.htm - Thanks Nandini and Spluch!
See also: Bulletproof Toilet, previously on Neatorama.