My guess is that the "old equipment" market is similar to the "old car" market. (...)
Well, in some way I am hoping you are right. However I have been checking prices for old, reasonably quality CRT equipped scopes, and I'm not convinved they have simply become fashionable.
Apart from a few, well known top models, like the Tek 2465 family, then the prices are somewhat similar across *all* analog scopes, which doesn't really make sense. If people bought them for nostalgia's sake, or as a fashion item, then I would expect particular models to stand out ('67 Corvette') on the pricing scale. Similarly, if the market consists of experienced hands looking for a good analog scope, then I would again expect some models to stand out. In this case the buyers would have preferences, like the Tek 2465s, based on technical merit.
But apparently the prices are all a wash, once we look at models below the very top. It doesn't seem to make much difference whether it is a 465, 2225, 2235, 2245 or a 2445, they all cost more or less the same. One possible reason for this could be, that the buyers doesn't really know what they are doing. Meaning they are often beginners when it comes to electronics.
Maybe people have seen Dave's video about the $50 eBay analog scope. In that case some may have gotten the impression, that if a little bit of analog scope is good, then a lot of analog scope must surely be better? I hope this isn't the case, because that could be a nasty trap for new players. The experienced hands on this forum can diagnose and fix trivial problems with passive components, if for instance their $400 Tek 2465 develops a minor problem.
Yet to a beginner it may not be such a good deal to pay $300 for an old scope, as even a trivial problem may be insurmountable. If you buy an old 2225 for $50 and it breaks soon after, beyond your ability to repair, then you haven't lost too much money. But giving $300 for a more or less random old scope, and hoping you will be able to save some money, compared to buying a brand new DSO, may be false economy.