I think there's number of parts in play and it's very hard to tell what the final bid's going to be. Pedigree is important, having the right hands on the car through the process can help drive up prices and for the record Sven Larsen was the expert on this one. I cleaned the engine bay with a scrubbing brush and took the parts to be plated.
The restoration on his own silver coupe a few years back documented here shows his level of expertise and detail and why he's so widely respected in this community. He knew this car and recommended I purchase it from the previous owner. He then applied those skills to my coupe when we rebuilt the engine, subframe and drive line etc.
Having a premier shop like SFDon's that only works on coupes restore your car will also add significant value especially for those who understand how difficult it can be to put a hand made car back together the right way and know every detail involved. There's a cost for that type of work and it's worth every penny especially to those who can afford it and for people like myself who are unable to do the work ourselves. I think a lot of buyers on BaT who love these cars have plenty of money but no idea how to work on them or even who to take them to when they need work. There's a premium in buying a car that you know out of the gate is sorted, and you can just jump in and enjoy driving it and only have to mess around with small issues when they go wrong.
Color can also drive up the price. Word from the Bay Area is that blue's seem to be incredibly popular right now so if you have all of the above in a freshly restored and painted blue coupe this can also drive up the price, however from what I understand restoring back to original color can ensure you don't take a hair cut if and when you sell.
At the end of the day when Fred and I talked about where the price would land before he started bidding on this car I remember him saying it only takes a couple of crazy guys who want the car to push the price up significantly and sometimes that can be more of a factor in where these things land than the details of the actual car being auctioned. Luckily for me Fred's a crazy guy

and there seems to be more minted everyday.