How can I take away 20 thousand dollars or more off of the cost of the house?

Start by negotiating with the builder - do not accept the first offer...you should be able to get them to come down about 5% (if you are not locked into a specific builder, shop around with other builders to compare prices). Go with cheaper carpet/appliances (though you will pay for it later). Ask the builder where things can be down graded to save money (i.e., no crown molding, no chair rails, etc.).