Have you thought about using a fiberglass resin patch on it? Pick the stuff up at any auto shop, You'll need to get the kit with the fiberglass cloth in the package. Just prep the fender surfacw eith some sand paper, saturate the cloth with the resin, slap it over the crack, smooth it out, wait til it hardens, sand it down, and repaint both fenders. It would be good to do this on both sides of the broken fender. This will save you big bucks.
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