The bike has fairly high miles and has been bodged. You're seeing little things, but there's plenty of wear and problems underneath.
It's running and looks OK at 20 feet, but will you be able to live with it as is and just ride it? And if you do, how long till it breaks? The purchase price is the tip of the iceberg.
I say all of this so that you'll reconsider your reluctance to lowball the owner. You want "A" bike, so don't fall in love with just THIS bike. Buy it as cheap as you can - unless a bike has been taken good care of and has a good history you are headed for project city.
Tires, brakes, battery, and cables are probably on the fixit list unless they are brand new. Carbs are likely to need a cleaning. You have the springs and switches and so forth that you've observed. No recent valve adjustment or tune-up either, forget about timing chain maintenance....
YOU will have to make up for all of the stuff that the PO did not think was worth doing. If you knew how much time and money this bike would cost you in the next three years, I guarantee you'd be offering no more than half of his asking price.