If you're restoring a six pack car, that can bring $200k, or a hemi car, that can bring $600k, or 'vert that will bring at least $150k, then a $4k fender is not that big a deal.
But if you're cloning, or restoring a 340 or 383 car, fix what you got, stamp some Barracuda fenders, or wait for Goodmark.