I'll never be able to afford loudspeakers $20,000 and up so I avoid including those in my quest, especially since there are many excellent brands well below that available used. Every speaker that I've bought here came from an owner that cared about them - I've yet to have a problem with buying used speakers. (Magnepan, Thiel, Von Schweikert, Dynaudio...)
I've been in the wine business for 33 years now which is as befuddling and subjective as this hobby is. Most of the cult wines and rarities aren't even consumed by their buyers, they simply collect them!