Over pay for cashflow?

[Terry Majchrzak]

I'm currently looking at a Owner financed 3 unit commercial/residential building. I couldnt find any comps but my broker friend did and the price difference is pretty astronomical. 

however after paying the note holder, taxes, and insurance id cashflow still about 600 bucks. But there would be a balloon payment after 10 years and im worried that because id be over paying that when I go to refinance...i might get screwed...