So I did a bit of research. Here are my two approaches to hacking complex problems:

  1. Find who is doing it already.
  2. See how this problem was tackled by someone who had it worse.

For #1: See http://www.naturalbuildingblog.com/ They aim for simple to build earth-based houses for $10/sq ft. A good next step likely is to reach Dr. Owen Geiger.

For #2: See http://www.rebuildhaitihomes.org/ Looks like they started with fundraising.