I agree with Kary's answer. There are many issues if you are planning to put in some kind of central heating system, including the depth of the crawl space and room in the attic for
ductwork, whether the house is one level or more, and so forth. Your agent should be able to help you get bids.
Be sure to check with Clark PUD, 360-992-3000, about their ductless heat pump program. This
is being partly subsidized by PUD right now, and there is also a tax credit.. It's not cheap, but
it is currently the most efficient heating and cooling system available.