The last Habitat for Humanity House I was involved in as the manager of the project cost $90/ft for a rambler with no garage. Including donated labor on ROOF, electrical, trim, foundation and paint and other, this house was adequate but no mansion. The lot was also donated. Another $10 per square foot will get a house built in the twin cities as this house was out state Minnesota. Sorry, $100 per ft is no where close to reality in our market, let alone the twin cities. Try $150/ft and you are still in a huge variables with choices you have to make along the way.