$400 does seem kind of high to me, but the rechromers know there aren't too many business' doing this kind work any more because of the EPA, and of course, they still need to make a profit.
Still don't know if 70 Coronet repop's are out there or if they are, what they cost.
If you need a couple places to call here (Chicago area) to compare prices, PM me and I can give you the ph. numbers. They gave me prices right over the phone without even seeing the bumper.