Hello! We just bought our first home at a steal! However, it does not have central air or heat. It has a gas wall unit for heat and window unit for air. It has a crawl space under the house which I assume all the duct work would be run? It has a lowered ceiling? So I guess the dust work could be put here? Not sure but my main question is, what is a ballpark figure We are looking at on spending for central heating and air units. We will more than likely do the insulation but a price on that would be awesome too. We live in Oklahoma. I know the price maybe different for each state/ company but maybe a general ball park figure could give us an idea on what we need to be prepared to spend.