Gas and Oil Home Heating Furnaces - DIY heat upgrade?

I am in the process of purchasing a home that is currently heated by wall can-type Cadet heaters. I would like to upgrade to a gas forced air system to increase efficiency/lower heating costs. There is adequate crawlspace or attic area to accomodate a reasonably compact furnace. All ducts and returns would have to be installed, as would the heating unit itself. Is this something I can do myself, or would I be better off contracting it? How much should I add to my guesstimate of the overall cost of the project (1100 sqft home in the Pacific NW requiring about 48 MBTU) if a contractor is involved?

Installing HVAC in attics & crawlspaces is a gruesome, intense job that takes much thought & planning to do. Takes many years of experience to do it RIGHT. There are many, many do`s & don`ts. Call a couple of local HVAC pros to get some estimates. Seen to many DIY jobs that was a disaster & had to be redone.

Thanks for the reply...

After looking at my available space, I think it would be more practical and heat-efficient to have a furnace mounted on floor-level (I have a spot I can give up). If I go this route, is your recommendation the same, or can I do it myself?

TIA

Floor level would be much better(in my opinion) but it is still a job best left to the pros. If you are handy at electricity, gas piping, duct work, sheet metal, venting, brazing, plumbing, refrigeration, and construction, by all means, get a book and installation instructions and go for it. You would save quite a bit of money IF you could install it yourself. Good Luck.