I typically start with the numbers provided in the offer memorandum and any marketing materials, then tweak the numbers to try different scenarios.

Material cost of the door is $800.

The owners don't want you there if your not working for them, you had access prior to keys and other sensitive materials so they want you gone...

Will the estimated $12K more in materials be worth it in increased volume? 

The total price using the finish level requested was $6900 for labor and $1500 for materials for a total of $8400 before taxes.

If it works and he gets another 100 million users to sign up or retain then it's like a double win for the FB team.  

(for my mother)Add master bathroom on second floor (would be placed directly above the kitchen and across the hall from another bathroom)All new systems (2 Zone HVAC, Plumbing (copper pipes), and electrical)I intend to use Spray foam insulationThe entire house would use low-mid tier materials with certain splurges(hardwood, kitchen cabinets)This will not be a rental, I'd live here. 

In regards to what I've done so far as a real estate investor...I'm a part of my local REIA and attending any sub-group meetings, I'm reading a LOT of material and working to find my first deal.  

The Mortgagee may want to retain their security as a Mortgagee for the sake of foreclosing junior interests while agreeing to take the remaining interests from the Borrower to legally direct the property.  

What we like to do is provide our PML  the contractors scope of work/ pricing, and provide them with a change order in the event we need other materials.