I live in a cheaper market with a lot of sub-75k properties.

They literally wrote the book on midterm rentals and cover how to analyze markets.

Yes, Builders have a lot of margin that they are working with typically because they set the market and manipulate the home prices.

With the economy and market as they are, should I continue aggressively paying down the HELOC to potentially borrow against again or should I just pay the Interest Only (IO) payments and seek other funding at the current day higher interest rates?

It is not on the market but I have an investor who is interested in purchasing it. 

New constructions in the neighborhood are selling for a significant amount above construction costs (double or more the market value of the land).  

The facebook groups are a great place to find mentor programs and such in your local markets 

Dba is typically for marketing purposes or if you are in another state and that name is already issued

We are a small shop in the Philly market and we try to stay in our lane. 

I'm still not following what you're saying about where the list service obtains the "current market value" of the home.