I would agree that a good body shop should be able to fabricate parts significantly cheaper than sourcing new fenders + shipping etc.
The GP4 cutouts are pretty big, but even if they are too small they have all the wheel well rolls and any gap should be an easy fab.
You have plenty of sources here for detailed photos or measurements. Have you got to the point of stripping back paint to see what you really have? It almost looks like the flares were formed from cut and stretch of the original fender?