According to the article, a two-bedroom cave in Galera, Granada, Spain, is going for under 90,000 euros ($117,000 USD). If you don’t have that much to spend, you can try for the nice “restored” 13-room cave house with three bedrooms, in Urgup, Cappadocia, Turkey, for a modest 140,000 lira (about $95,000 USD).
While I wasn’t able to follow the links the article suggested, one link worked: escapeartist.com. And there, you can read about the eco-benefits of cave-dwelling. (W., eat your heart out!) I also clicked through to a link about a new “development” in Spain, offering different 2 and 3-bedroom model set-ups, starting at around $130,000 USD.