@Tom DohertyWith new duct work around $6k, without duct work $4k

Assuming the ductwork is fine and assuming this isn't a 5000 sq ft mansion, you can get a new unit for around $5500 including a new furnace. 

I'm no expert but that sounds like a $8k - $10k job if you need to run duct work. $3k - $5k should cover a single unit with a lot of capacity.

You can always offer lower on the property factoring in new furnace cost, instillation and potential duct work. 

If the ductwork was sized for a gas furnace and air conditioning , it will be undersized for a heat pump .

I bought a house that will need a full gut renovation I am just curious to see how much it has cost to put in a furnace, central air unit and full duct work.

Ductwork under house obviously has holes.

I'll be closing on a triplex soon and 2 of the 3 units share duct work (furnace/ac).

My quotes from 3 contractors on each house ranged from $12,000-15,000... these houses were two story with no ductwork.

We have done ALL the work ourselves except for finishing the drywall.I will do a whole RENO thread once its done, but here is just a quick overview of what we have done.Whole new Heat and Air unit, switched to gas, and moved duct work from under the house to the attic.