When the current crop of 50-year-old-plus Unitron and Questar collectors reach old age and attempt to sell their valued instruments, they may be in for a rude awakening to discover that the market for relatively small-aperture refractors and catadioptrics has itself become quite small, regardless of any supposed mechanical and optical perfection which the instruments might possess. It will not be our world any longer, in which Sputnik and Moon landings were childhood wayposts, but that of our grandchildren and great-grandchildren, who will live in a world that we likely cannot imagine at this present time, and who may well have but little attachment to, or use for, their ancestor's archaic instruments, no matter how finely crafted.
As Horace wrote, "Eheu fugaces labuntur anni"...
Boy does this paragraph ring true. I believe, as you apparently do, that the price of certain classic instruments such as Unitron telescopes is largely nostalgia driven. In our youth back in the 50's and 60's, these were highly coveted but unobtainable. Some of us in our 30's bought our first Unitrons and some waited until later. (I am now 60, but was 33 when I got my Unitron #152 4" equatorial). The young adults of today entering the hobby did not grow up in an age where Unitrons were advertised and much sought after.
I feel that interest will wane and prices will stabilize and likely even fall (factoring in inflation effect) as many of us assume the horizontal position.
Once everyone who wants a Unitron (or whatever) at a good price, gets a Unitron at a good price, the bubble is going to pop. Think of it as the Telescope Bubble.