I'd also send it registered mail or deliver it to the house yourself. 

Also, as long as the house appraises, taking broker commission and using it against down payment and closing costs means lower cash requirements for me which increases my CoC returns.

A 5 unit multi family and a duplex plus my dad's house.

AirbnB, long term rentals, how large is the house,  how many rooms... your message should be extremely specific.And do not neglect Pinterest.

It's a huge house with tall basement ceilings.

So in Real Estate, say your doing a "volume model", let's say sec8 housing.

As others have said, the best thing your son can do is run far from this deal, buckle down, save his pennies (he probably already is doing this), house-hack, and improve a property with sweat, hard work, developing a DIY skillset, and self-managing tenants. 

So back to being a real estate investor: the only way to be one is to buy a property and create value out of it, whether through finding a below market value house and selling for a profit, or renting and creating cash flow.  

Spend a little more money than you might have been planning to, buy in a better area (i.e. not a “turn key” 100k house off the mls), and self manage.

Small multi-family is hot right now due to house-hacking (low barrier of entry), and future cash-flow.