IIRC, the reason machines like the C65 fetch so much is that they are true limited production machines. They were all prototypes. Until now I was not aware a machine that not only worked (ALL the ASIC's were present and the ROMs would function) but was also as complete as this one even existed.
When you look at the price of something you need to take into account three things:
-Industrial demand: Companies who for financial reasons require older components to maintain legacy machinery
-Historical demand: Institutions, companies or museums looking for components or specimens to add to or maintain an existing specimen
-Hobbyist demand: Popularity amongst a group of people who share similar ideas about a company and/or product
One or all three of the above can sway the price of an object.
-Paper tape punch units are still hundreds of dollars used because of high demand with older milling machinery.
-Xerox's early GUI products like the Alto, Star or Daybreak were peculiar first steps in what the first commercial concepts of a GUI might be. (or would not)
-Apple's compact macs are expensive because OH MY GODDDD IT'S STEVE JOBS! THIS IS HIS BABY HE DESIGNED THIS IN HIS GARAGE WITH HIS BARE HANDSIN1959IREMEMBERTHISASAIDDIN SCHOOLTHISWASSOAWESOME.....
Stupidity alone or some statistical price analysis tool (I'm looking at you Terapeak) cannot explain it.
In relation to the C65....
-Industrial Demand: "We need this complete machine at all costs in order to reverse engineer and remanufacture new machines."
-Historical Demand: "This machine is immaculate. I want this machine procured for documenting and storing under glass in the main hall."
-Hobbyist Demand: "Wow! This will look amazing next to my Bill Gates autographed Altair 8800 and Steve Jobs autographed copy of NeXTWORLD! Good thing Google just gave me that promotion!"
Comparing the value of an SGI no compared to ten years form now is....kinda a poor example.
It's like being surprised that the SPARCstation 1 I got ten years ago was worth nothing and ten years later it's STILL worth nothing!