Don't bother blaming the guru or the course - the gurus aren't qualified educators, and the course material has not been vetted by educators.

Look at finishes, quality of materials, lot sizes, house size, age, etc.

I've been checking out articles, forums, and educational materials for the last month or so.

If you're really doing that large of a scale, I imagine you have a warehouse where you store materials, right?  

Don't have much to materially add here, but @Jay Hinrichs is right.

What material would you use to fill/fix those holes?

Some advice:Hacking a house you lease or have an option on doesn't give you the authority to make improvements, you may have building code issues and the owner or contractor will need to pull permits.It was mentioned you do that at your own financial risk.Since a Realtor is involved, they may very well advise (and rightly so) for the owner not to allow improvements made from a handyman investor, they will be concerned about the quality of work and so will any lender and appraiser.Contact the insurance agent, most policies allow small improvements to be covered along with liability (not workmen's comp) but generally materials on site will not be covered.

As materialism continues to grow, we accumulate so much stuff we don't need.

Most builders are cost plus meaning they tack on a percentage based on the cost of materials.  

Right now it looks like you would have a cashflow of $9245 but you are missing so many factors like you're going to be living in one of the units which is going to take away from that number also are you going to do repairs/maintenance if so you still need to put something in there for material if not you need to budget for that altogether which eats into that money.