We went with highest offer got a counter asking $20k more and reluctantly signed.

But as a first-time buyer, there are so many things in the process I am just not familiar with, including how to structure the offer, being able to view listings on Costar, doing due diligence, etc.

I'm thinking about offering an owners' rep service for folks who want to invest from out of state but want an independent opinion from their broker. 

From a negotiating standpoint, you could use the heloc to make a "cash offer" with no financing contingency and still get a mortgage during the process as long as your closing timeline provides the time to do this.

A bank does not offer a 30 year fixed conventional loan for a 12 unit commercial purchase.

I've been looking at some of the online lenders (Better, Figure, Rocket Mortgage, etc) and while they offer a decent product, perhaps there is a lender who is local to Indiana that would offer a HELOC with better terms? 

This creates two loan payments ($100,000 of equity and $300,000 on the new mortgage).Key NumbersHome Equity Loan Interest Rate: 6%Mortgage Interest Rate: 7%Rental Income: $3,000 per monthExpenses (management, taxes, insurance, maintenance): $800 per monthIncome and ExpensesMonthly Rental Income: $3,000Monthly Expenses: $800Monthly Mortgage Payment: $2,000ExplanationThe investor earns $3,000 in rent each month.They pay $2,000 on the investment property mortgage and $800 on other expenses.This leaves $200 profit each month or $2,400 per year.However, you have to pay $6,000 interest on the equity borrowed.This leaves you with an annual loss of $3,600.While the rental property generates positive monthly income, the interest cost of borrowing the initial $100,000 results in an overall annual loss.

There are other expenses beside the loan that will need to be accounted for such a grounds maintenance and insurance. 

For income reasons, you can qualify with a non contingent offer letter (salary position) before you start working.  

The reason I pulled back from my marketing to owners of these asset types, was when I began hearing that they were getting anywhere from 3-10 offers per week from would-be investors.. and that was in 2017.