You asked a very interesting question, one that many buyers are curious about. The answer, unfortunately is, it depends. For one, is the house already built, such as a model home or a "spec" home. A spec home is a home a builder puts up, speculating that he can sell it. In this market there are few of these. A model home might have many extras to show prespective buyers a sample and when it's ready to sell, can get a better buy than a new home to be built.
If you are building from scratch and negotiating with the builder, keep in mind that the builder has the cost of building the home, then he tacks on his fee which runs somewhere between 20-40 K on homes under $500K then there is the real estate fees and adjustments to the market. The basic price has very little if anything to adjust. Your best bet is to negotiate on the extras. The builder would probably get those cheeper than you can and if you really want them, this is a great place to negotiate. My advice is give the builder this base price but add into your offer things like paving, moulding, built in, appliance, lighting and kithchen upgrades, wall up attick and the like. zI have an article on my site about things you need to know when building your home. Please feel free to read on.