House does not have duct work, has 10 ft ceilings.

I have waterlines in the bathroom that are not accessible from the crawl space, they are only a few inches below the subfloor and there is old metal ductwork right beside it, so there will be some heat coming from that line. 

I spent double the estimate.2) House has no attic for HVAC installation, also no space under the house for the duct work either.3) The boundary line cuts diagonally towards the edge of the house and cuts off some portion of the lawn.

I've been cleaning the floors with enzymatic cleaner and trying to air the house out but despite some improvement the odor is still too objectionable to move in.I didn't know until after purchasing and attempting to clean, that pet odors tend to be persistent and difficult and expensive to eliminate as contamination is absorb into the floors and walls and even the furnace and duct work.

Duct work is in place for the furnace.

Come to find out, cats had destroyed most of the old ductwork under the house - another $1600 (wasn't expecting this one!).

If you are just swapping out a new FAU with furnace, condensor and evap coil and not touching any ductwork and don't have to replace line set and can use the existing electrical, you are looking at about $4500 or so for a 4ton unit.

Blinds and window treatments are out for sure.You will not be able to fully remove it from your ductwork.

If you have the option a mini-split can be used in a bigger space with ductwork already in place and a booster fan.

The building is separately metered with each apartment having their own furnaces and existing duct work, but with window units and not central air or ductless systems.