It's important to know what market rents are for what you are analyzing, many properties are super under rented and you have to get them to market rates. 

Quote from @Jacob Sherman: What type of loan products are you in the market for ?  

The guru your son is learning this technique from is likely not telling your son that the deal will almost certainly encourage your son to get an "off-market" deal from a "wholesaler" who is unlikely to properly disclose the details of the property or encourage an inspection. 

It is still a seller's market in many geographic locations, so you can ask potential buyers for an extended closing period and/or with options to extend the closing period. 

You may also be able to "make your market" if you can hit a critical mass.

What is the property appreciation in that market? 

Quote from @Kevin Hintz: I can totally relate to the tight market and how hard it is to find deals.

Last year, I purchased a SFH under market at 7.65% interest rate and did some rehab to up the value.

I’ll also start integrating more storytelling in my outreach and marketing to make it stick with people.Thanks for sharing this—it has inspired me!

(Available time, money, income, family situation, credit availability, time horizon, real estate market location and phase, medical situation, etc etc.)