Look closer I think price is core included but no longer required to be exchanged, many folks hanging onto their own core "just in case", leaving them short handed to fill orders I would suppose, (old trucks/PCM production down/supply-demand forces at work).
I suspect if you did go thru with the reflash you would see some refund/reduction if you did indeed return a core, IMO no need to hold onto a "just in case PCM" on old trucks out of warranty.
FWIW I've got years on my 1st reflash, I held onto the core when there was still warranty on the truck and a dealer might try to decline warranty because I had "modified" my truck, in all that time there has not been 1 PCM induced issue, those are the rarest of the rare issues for the 6.5.
Once my warranty expired, I sent Bill my old core, we traded it for another goodie I needed at the time, I've found Bill to be very open to this barter system, he needs
WORKING cores, I need goodies, so if I come across great deal on a core I plug it into one of my trucks, test it and then call to see what other doo-dad he has on the shelf I
"NEED" and we can trade some on, couple of times I've just sent them to him cause he's a nice guy


Not saying he'd do this for everybody, but I'd call him to discuss options.