Before we go full in house, we are really trying to dial in the quoting process, specifically with putting material lists together.

*Renovation Costs – Includes labor, materials, permits, and unexpected repairs*Holding Costs — Utilities, property taxes, and financing costs during the renovation time.

I work for a building materials company now and took their online game from Zero to very engaged in the past few years and it's been really fun.

If you are going to rent it and want to take advantage of the tax benefits be aware of material participation requirements and limitations on personal use. 

In your case going to a fifth unit as noted above could actually reduce the value, so I'd be cautious of that since that materially degrades their collateral.

In CA (my market) the seller is required to make honest disclosure statement and you can collect for material non-disclosure.I suspect you already have learned that you need to check the status of all permits. 

From day one they promote themselves as high-quality, safe, service oriented and experienced.  

Look at the pictures to evaluate the quality of the materials and workmanship of the comparable sales and align your ARV accordingly. 

I needed some extra financing on my first rehab and opened several 0 apr credit cards which I used for materials and payed them off before any interest.

Cash flow is definitely the biggest challenge; both in terms of finding properties to buy that cash flow with a loan on them and just company wide given interest rates and labor/material is up and, at least where I'm at in Jackson County, MO, taxes are way up too.