There is no magic when it comes to keeping building costs to a minimum.

The basic rules are:

• Build smart. If you build to good environmental principals, it may be mean a higher initial building cost, but it will save you allot of money over time on running costs like heating and cooling, and it may just be a more enjoyable house to live within.
• Keep building area to a minimum. Build only what you need.  Make the most of it.  Make each room a room that you will love to be in and live in.  The initial cost of solar electricity is the cost of a bathroom, and it pays itself off over time.
• Choose local and cost effective finishes and fixtures.  The cost of finishes and fixtures can be deceiving because the cost of the super dooper item may only be hundreds of dollars instead of thousands, but spread over an entire house, these items can add up to a lot of money. When selecting finishes and fixtures, do a spread sheet so you can see the cost of the options and how it all adds up before you make the final decision.