Word of mouth. Same thing in many other brands. Certain ones have a 'reputation', and some folks are willing to pay for it. Some people get listened to. And their opinion matters, (not reality for a percentage of the buyers) And all it takes is a few percentages to bump a used item from no one whats it, to high demand big prices.
My favorite example of a decent but way overpriced audio toy is the Audio Research SP-10 mk2 old but venerable, it has a great reputation. So much so it is selling for more than the original price of $3000. I owned both a SP-10 and a SP-15 at the same time. The 15 trounces the 10. I kept the 15, sold the 10. Yet folks still clamor for the 10. Why? the REPUTATION.
My favorite example of a decent but way overpriced audio toy is the Audio Research SP-10 mk2 old but venerable, it has a great reputation. So much so it is selling for more than the original price of $3000. I owned both a SP-10 and a SP-15 at the same time. The 15 trounces the 10. I kept the 15, sold the 10. Yet folks still clamor for the 10. Why? the REPUTATION.