[twobjshelbys]

The best fiberglass repair place in my home town was the boat place...

That said, for a door you'd be best to repaint the whole door. A good painter an visually blend the door edges so you'll never see it.

But if a golf ball sized check is keeping you from buying it, you should move on. As a seller I wouldn't spend a bunch of money only to have someone come back and say it's unsatisfactory.