Looking at what the head cheese in Milwaukee will sell you new, I would say well under $300 for a good used one. Have you asked your local dealer? They don't list a stock Fatboy rear fender on the website, but they do show a bobtail fender. Painted it lists in the area of $370-395 depending on which paint it has. $125 will get you a new one primed and ready for your paintbrush.