There are two primary methods of reducing costs of construction. The first is cost negotiation and the second is cost shifting. These two methods have several tools in each to achieve overall price reduction. The following describes each method and the respective tools within each method that you can use to achieve overall cost reduction.
In many industries this is known as risk shifting. In effect, shift onus of the cost associated with building the house onto the supplier and or vendor. The best tool for this is a more detailed contract between you and the vendor.