His source, probably like most car dealers in that area > https://www.manheim.com/

It sux because you have to be a registered car dealer to buy at this auction.
I've been to the Manhiem, PA location many times and OMG is this place impressive.
Massive property with anything you can imagine running through the auction.
The Import/Exotic Highline Nights are SICK!!!!!

 

This is a nationwide search - not as many as I'd thought............

 

IMHO ebay is a good representation of wholesale values. If you pay more than ebay price, you are likely overpaying. If you are selling, it is likely the floor.

 

Also, re: Manheim or Co-Part. Look in to the auction fees, you can easily add about $700 to the wholesale value of the truck to get out of an auction with the truck. Best bet is to get it from the dealer or private seller before they trade it in.

 

 

One company I represent for insurance is Hagerty. They put out weekly info on collector cars and their peculiarities as well as values. Their figures are based on three things primarily:
What are the cars selling for
How many new quotes are they processing (aka demand / like volume on a stock)
Condition or grade of the car

Now, D2's haven't peaked yet. In my weak newcomer opinion, they are still depreciating. Maybe they are climbing-not looking for a pissing contest on that.
So we have representative sales data from eBay (hard to argue nationwide exposure). Collector cars look mostly at places like Mecum and Barrett-Jackson.
How much demand is there? Are people beating down your door to buy a D2? If yes, that drives the price up. Simple economics. I think that may not be the case as these vehicles obviously require a masochist with mechanical, electrical, and hydraulic capabilities. As more go to the crusher, the supply will be shorter, which will drive the price up. Of course the rover got longer in the tooth waiting for that to happen too, making good examples bring even more of a premium.
Which brings me too my actual point.
My D2 is not a pristine perfect as-delivered specimen. So it is NOT WORTH WHAT A PRISTINE PERFECT AS-DELIVERED SPECIMEN IS WORTH.
I see it all the time. A restored original 70 Mach 1 sells for $70k on TV in Scottsdale. The next week a guy comes in and wants to insure his unrestored original 70 Mach 1. We discuss the value. Its got some rust, interior shows its age, 150,000 miles, custom wheels, you get the picture. Its not a $70k car but THEY ALL THINK IT IS CAUSE ITS "JUST LIKE" THE ONE THEY SAW SELL ON TV.
Condition is everything. The trend now is that "customs" are bringing more than originals. Old cars are depreciating fast regardless of condition cause the newer generation buyers with expendable cash would rather have a Toyota Supra than a pre-war Cadillac. They can't have fun with a big pre-war car, but they can with a 80's sports car.
Its a moving target. D2's will get their 15 minutes. What condition yours is in when that day comes will determine what it is worth, and there is no better indicator than an auction with cash buyers. If they earned the money; they will likely know how to spend it.