The area you're discussing is near the Lilly facility on Meridian. 

I'm sure there are lots of legitimate people who need a comfort dog but the majority of tenants that are using this "reason" don't really have a medical concern.

For those outside of the medical field that may or may not have any idea that these positions exist, we live in a 5th wheel and travel from area to area every 3-6 months. 

The amount of Health professionals that live and work near the "Medical Mile", number of colleges with hungry student renters, and Amazon just greenlighted their distribution center here a few months ago. 

This documentation is usually a letter from a medical doctor or treating therapist who can establish the disability and need for the assistance animal.

What are the best ways to source self storage facilities for sale?

That happened totally unexpected with having those medical problems but I am still hoping that that will pay off someday.   

I currently Flip, Rent, and own a self storage facility.

I just find the prices a bit too high for rentals in Denton proper, but if you are patient and look around to communities like Ponder and Krum and Sanger, you might be able to find things that you'll be able to rent readily to people who work in Denton (county government, universities, very large medical complexes, etc.) but cannot afford to buy in Denton.

I have a huge lot 1.5 acres and will have completed an on site laundry facility and am drawing up a 12 unit storage facility.