Driving for Dollars on rentals?

[Nat C.]

I've been assigned to find a rental property for a businessman. 

He wants a minimum 3/3 house close to the city area in Miami. House must be in a good area and be modern. Budget is fairly flexible but I think under $5000 is desirable. 

It's a pretty specific criteria and he has said he would like me to find a rental directly from owner, not through an agent. Most people who own these high caliber homes are not the type to self manage. He wants me to apply the same formula of Driving for Dollars to rental properties. 

I can't fathom a way I can achieve this. Does anyone have any ideas on how I can find mini-mansions for rent directly from the owner?