IMO all of the value is in that front cover. If it's broken, $100. If it's not broken, $1,000. That's just because I've never seen one that wasn't broken in person. Pretty sure the first person to sit in the passenger seat in 1970 broke most of them.
One thing I have found about NOS parts is that they are sometimes still around for good reason. For example, I used an NOS fender for my 70 cuda and the headlight bucket area needed to be reworked because it wasn't spot welded in the correct orientation. It probably sat on a shelf after they...
Do you know who manufactured these? I didn't know they made reproductions grilles with the part numbers. Of course, I am definitely not an expert in this area.