We built a new house 3100sqft, 4 Bed, 2 ½ bath for $310,000.

I'm wondering how much specifics I need to include for each line item. 

Foundations and framing were built better 100 years ago and there are some advantages to older homes.   

However to save money when she had the house built, she left the basement unfinished--it is just studs, insulation, and windows/doors, plus plumbing in the foundation.

But if you're able to figure it out and get it built, you can rent out the units and essentially BRRRR it and pull some/all of your equity out to repay your debts, yourself, and potentially keep the investment cycle going. 

Nearly all of our business came from the relationships that our originators had built over the years. 

Quote from @Gaetano Citera: I would look at what has sold for Prefab verse stick built..

With 30 years of experience in real estate and now owning a quadplex, duplex, and a condo STR, you’ve already built an impressive portfolio.

I’ll also amortize large items like roof over 20 yrs, and then add $100/mo/unit for general repairs.

I know of some folks in KC and Memphis doing new builds like this, but they are doing it within a much larger and long-term project that includes upwards of 300-500 units built over the course of 5-10 years.Assuming you're looking in Columbia, do you have a "B+/C" neighborhood in mind?