Also, adding central air is expensive if the ductwork isn't already in place.

Mini splits are amazing because you avoid running ductwork through the walls and ceilings, huge time saver.

New fans, new duct work, new dryer vent, new flooring, some new cabinets, electrical work, mold damage, sheetrock and texturing, sewage pipe broke in front yard from tree root (replaced pipe), leaking faucets (replaced), etc...

(Thought 9-10k is good including ductwork, etc.)

Air:  Heating and cooling, what type, all rooms covered, thermostat, window units, everything working, if forced air, need servicing of ductwork, etc. age function of unit, type of fuel used. 

I did not know that the heater ductwork was not connected or that a main beam like 10 x 10 that held up the entire house since 1900, including a second story was old termite (none active) destroyed for 4 feet and no longer held up anything. 

Putting at ground level DIY $3000, if duct work needed $3500.

Has anyone done exposed duct work in a SFH or condo? 

We knew it was load-bearing and would need a beam installed, but when we tore apart the basement we saw that the wall was filled with ductwork in each stud cavity (4 runs total).

I paid an HVAC/Plumbing company 30k to install all new duct work, new mechanicals, and all plumbing in a flip.