The math still does not work out to $8,340.

What's really the math logic for the lender to charge the LP $20 million, $40 million or even $1 million ?

@Beck DeYoung  you are facing a simple math problem here.

There are so many forum posts from investors who buy a random property thousands of miles away based on recommendations from people they don't know and unrealistic spreadsheet math, get crushed by capex, and give up. 

Upfront expenses and monthly payments must be considered when calculating the return on your investment.EXAMPLEI will provide details below, but here's the short version for those who hate to read or do math.

Napkin math on offers to get a rough idea, then a deep dive when under contract.

Hey Cameron,Sorry for the delay,  in math terms 6% is 1.5 times 4%.However, for tax purposes it is not that simple, for your primary residence you get a lot of tax breaks such as not paying for schools, and an exemption of the first x $'s etc.  

Do the maths. 

I did the math and they'd owe us $130,000 if this stands.I figure they will fight this order with everything they have.

I'd do whatever the math says works best, and don't fall for the low rate 1st fallacy.