Rustoleum 7784, charcoal gray, spray can at Lowes.
My opinion is that you'll be more satisfied doing it yourself. A machine that has been sitting outside for two years in a location with 60 inches of rain a year and 95% humidity (Lake Charles is only 30 miles from the gulf) is going to show some rust.
The other point is why would you sign an affidavit swearing that you have received manuals when you have not? The point can be made nicely that when your manuals are delivered, you will be ready to clear that item. The monkey should stay on the salesperson's back to get the manuals.