My guess is that how a DE shaves depends mostly on the head design. Things like blade gap, blade exposure, the curve of the top cap, how well/ridgidly the blade is held in the head and other parameters all have a bearing on it. Makes for an almost infinite number of combinations and that makes it a tinkerers delight.

I was lucky enough to get a Wolfman WR1 OC head with a 0.74 blade gap before the first of several price increases and can say the fit and finish are near perfect and stainless steel beats the heck out of a plated finish. You are just paying for that and being made in low production volume. I thoroughly enjoy the shaves I am getting from it. That said there are several other modern DEs that I also thoroughly enjoy the shaves from as well. Those others range from the Muhle R41, Merkur slant, plastic Fine slant and Merkur 45 bakelite. There is no direct correlation between price paid and how well a DE will shave from what I can see.

Vintage DEs are another can of worms that add rarity and condition into the equation as far as price goes. There seems to be no guarantee, regardless of price paid, that a vintage DE will shave any better than or worse than a modern DE. The shave quality varies as much with them as it goes with modern razors.

It is all very similar to the pricing of modern and vintage straight razors.

Bob