Rather than comparing the present day pricing of vintage components to their original cost, IMO a more meaningful comparison would be to compare their present day pricing to the prices of currently produced components which could reasonably be considered to provide comparable performance.
For example, a new Magnum Dynalab MD90 tuner sells for about $1400. While I have no specific knowledge of how its reception capability and its audio quality would compare to those of an MR-78 in top condition, I wouldn’t be surprised if the choice could go either way depending on individual preference. So from that perspective an MR-78 selling price that is not a great deal less than its original cost of $1699 would seem to make sense. And the same goes for the earlier tube models, such as the MR-71 (which today, in top condition, is worth a good deal more than its original price of $400).
And viewed from that perspective, paying several hundred dollars (more than their original price), or in some cases upwards of $1K, for well restored examples of the better tube components from the 1950’s and 1960’s, such as those mentioned above by Mesch as well as models from H. H. Scott, Fisher, Pilot, etc., would also make sense for a lot of listeners. Although in the case of some of the most desirable and/or rare models present day pricing certainly reflects a collectibility premium to some degree. The tube products of the original Marantz company, models 1 through 10B, being among the most notable examples. I believe a pair of model 9 monoblocks in excellent condition would go for $20K or more today, and a pair of model 2 monoblocks for $10K or more. None of the Marantz tube components approached $1K originally, even though they were quite expensive in their day compared to products from most other manufacturers.
Regards,
-- Al