Commercial Real Estate ( Just Nuts And Bolts )

I am dealing with a very hard seller of Commercial property in Cabarrus County NC. The sellers are from Brooklyn, NY and do not understand the local market. They are under the impression that all commercial property no matter where it is located has the same value. the market here has taken a beating with several companies closing their doors and moving jobs elsewhere. Which makes for an abundant supply of empty buildings available. In the last threeyears we have lost over 8,000 jobs in this county and the trend is continuing. My question is how do you make a seller who is out of touch realize the severity of the situation here. I have sent them all the data about the area and they seem do dismiss it as me trying to get them to sell their property dirt cheap. How do you convince them when all others things have failed. If anyone can give me advice on how to approach this it would be greatly appreciated.