Then I saw new Thorens and Garrard selling at $15K and $20K. The high price tag must be due to the popularity of the vintage models and strong following. The popularity may be due to their true superb performance or possibly due to hype or nostalgia, or something to do with cult level status.
You'd be surprised. All of these play a part. Except hype, a word you seem to use as a catch-all for anything anyone likes more than you think they should. But whatever. There's a point here worth making but its going to call for opening your mind and looking around at the whole big wide world. By you I mean you the reader not necessarily just you the OP.
I've been a Porsche guy since high school. Back then a new 1979 911SC sold for about $25k. By the time I could afford one it was 1991, they were depreciated to about $12-16k, and I found a very nice example for $16k. People mocked me for over-paying when $12k was the going rate, and sure enough within a few years its worth much less but oh well, its a nice car, don't they all go down in value anyway? Well now 30 years later its got another 150k miles on it and still a fine example and guess what? They go for like $40k now, ones as nice as mine anyway. The better the condition the higher they go.
What I noticed over my 30 years following these things, they all do this. Every single one. People get blinders on, something catches their attention, they figure has to be X. Which X could be oh its a GT, or its a Speedster, its the last of the air-cooleds, or X could be what you said, nostalgia, cult (another misused word like hype) status, whatever. Point is this is nothing special. Happens all the time. Don't be distracted by this one or that one. Pay attention to the trend. The all-powerful trend.
The trend is anything and everything that somehow manages to survive the ravages of time becomes worth a lot more. One Porsche guy refused to believe me, went looking for proof, was at least man enough to admit when he found a Chrysler K-car selling for $25k, about 5x what they went for new, crappiest car Chrysler ever made. Watches, clocks, telescopes, and yes turntables all follow this same trend. Try and find something more than 30 years old still in great condition that has not gone up in value.
(Priced in fiat dollars, which is the real problem. None of these has gone up in terms of real money, gold. But that's another one for another day.)
The market is thin, and the market is specialized. You can bet your bottom dollar that $15k turntable you're talking about is one truly exceptional example, nothing like what you have or are likely ever to see anywhere. That's why people pay the money. To have something special. And it is. All you have to do is watch the reaction every time I pull up at a gas station. People just naturally love intrinsic beauty that endures. Its not hype. Its in our blood.