Because without the monster shipping box they use from the OE vendor, you can't ship this that way. Even if I had a box, freight would be about $125 one way. And even if you wanted to pay for freight and I had a box, you take a 50% chance of having the UPS thrower damage it.
Whoever picks this up will get a perfect fender. If I ship it............it won't be when it gets there.
Anytime you go pick up body parts, try to do it in person and inspect them before you haul them home.
Also, if I thought this fender was worth $50, I'd put it in the dumpster. Or, I'd of advertised it as 'junk'. Considering you can't get a good used fender for less than $350 locally (this one is nicer than what Mustang Village sells)............your offer isn't reasonable.