Against my better judgement...
Another way of looking at fine, collectible double gun prices is through equilibrium price driven by supply and demand:
There's a finite (and falling, as more succumb to wear, abuse etc) number of fine vintage doubles. That's an absolute limit, which may sustain prices; but they're generally held by collectors who are at an age and stage they're looking to sell - good supply, temporarily. Gen X, Y, Millennials seem largely disinterested in the field - low demand. Until those generations get the bug, things look poorly for gun prices - which may be an opportunity if you think they'll climb again, or not, if you think it's on the wane permanently. The shrinking of hunting opportunities and general swing against hunting and shooting socially doesn't look rosy; against that though is a modest, but growing counter-culture of people who value vintage, handmade, craftsman-built stuff. Fine old guns fit that.
It certainly explains what I saw at the last auction I attended: lots of grey hair (of a couple of hundred in the room, I was almost youngest - at 40), plenty passed in after failing to make reserve, or sold below estimates.
Rocketman perhaps has some data on what prices have been doing over time?
