Private Money or Hard Money LendersIf traditional financing is a challenge, a private or hard money lender could fund the construction phase.

Get the timing wrong and you are looking at a downturn and loss of capital, at least on paper.Adding value is key to giving yourself the best possible opportunity of your investment making you money.

Do you need to get the money for the down payment?

If not I wouldn't bother selling as there is an incredible amount of money lost in buying and selling properties, so you have to make sure you have a plan to maximize the equity and actually have enough. 

Definitely saved a lot of money.

(cost of buy-down in dollars / monthly savings vs the free loan = # of months it would take to recoup the money spent). will you keep the LOAN at least that long?

Value of time vs the value of money

A Heloc is always going to be in 2nd lien position and you cannot borrow more money unless the heloc is paid off.

I actually think you would be better offering $1.5M cash and use a hard money loan for six months and refinance into permanent debt. 

That kind of money can easily be put towards your own marketing efforts and business.