From what I can see, and I'm looking at the pictures using my galaxy S6, most of the major areas such as the hatch landing / dog legs / rocker panels don't look bad as far as rust goes. It helps that it's the original paint and you don't see much blistering of the paint. The rust that he does show wouldn't kill the deal for me. I'd definitely try to get him down on the price, but I'd do the same if he was selling it for $2000. That is a good foundation to start from.
There's my. 02 and enjoy.
Daniel