These props were in good areas so I am guessing that is why. keep in mind true A class areas whould see majority of comps being sales to homeowners NOT investors.. homeowners dont care what the cash flow is or the potential rental income is only investors do..

(rents also peaked from $1900 to $2600 in 2 years)Sale Price  -             $360K - $370K in the area for same kind of units.            

An agent is not guaranteeing you a purchase or a sale.  

Your son is likely paying more than the property is worth, by definition, as the seller would almost certainly prefer a similar offer that was not subject to. 

It's a narrative that's pushed through social media, sales brokers, turn key operators etc.

Quote from @Caleb Brown: Is the property worth the higher price to pay off the loans?

The 90% they are paying you back is probably 1/3 of what they're actually making by you committing to a deal.

@Zoe Brennan You can use the info below to pursue either real estate sales or investment sales:)Why does everyone want to chase strangers – and ignore their own personal network?

I'd also add to that that you are paying a 20% withholding tax on gross rental income. 

If you aren’t saving the money up to buy another property chances are nothing will pay a higher rate than paying it towards your mortgage.