I have a bi-yearly contract with them to maintain the units and they currently have a new policy where they check for mold in the duct work by an intrusive method and they are finding slight mold growth and are recommending this device called Nasa Air Scrubber (~$1200 per unit). 

I am looking to buy window units hot and cold air functions for a property under Rehab - has anybody bought this lately and would you recommend any brand based?

I looked at various sources where this seem to be up in the air. 

His quote came in a little bit above what we expected for a couple reasons that are extremely boring to explain, but long story short we think if we sub contract out the electrical work associated with the install on our own and go with forced hot air systems we will be right in line for what we budgeted for.Painting in the common area and the 3rd floor flooring work should pick back up next week.

I'm often shocked at the number of people in Chicago who will pay $1,800 a month for a 1 ba apartment with no upgrades and window air conditioning.

The Building Code however could make certain requirements impossible to adhere to (such as light and air, egress, fire seperation, etc.) .

I'm from Bel Air, MD (north of Baltimore) and have one rental property which has worked out amazingly well so far. 

Are there air gaps in doors/windows?

Once we had it stripped down, we sprayed the floors down with Odaban (Home Depot) then aired it out a lot and ran an ozone machine for a few days.

So if I did the math....After Rehab Value = $220k (since I'm conservative; and I feel like I'm pulling the number out of thin air.