We meet every month, and are in constant contact with these individuals, in business relationships going a lot deeper than that.The second way is to contact a large group of people with the understanding that only a few will result in “deals”.  

Does that mean the actual manager or a local contact.

Thank you very much for the prompt response.I will contact them soon.

Look up market rental data to know if you're in a lower paying area.

I contacted Zillow about this issue but received no response.

Quote from @Keith Miller: Hello,My partner and I, @Brent Maier, are looking to find and contact multifamily owners.

With all this said, to answer your question of how you'd value this for a sale, I'd get a STR specific broker that's able to market your property as a turnkey STR with data on the rents, figures, etc.

Monster data base  tons of credibility with your RE clients one has sold to over the years..

Since your a hands on person and have contractor contacts.  

I'd have them sign my own lease on renewal and I'd make sure I had enough information on them so I can go after them if a legal issue arises such as employer and other similar data.