Yes, the high spenders are guitar collectors and restorers. I regularly get queries about these caps from visitors to my website.
So far, I've resisted the temptation to paw through my sacks of replaced components, even though I'm the kind of person who never throws away anything except solder blobs scraped off the workbench.
From what people have told me, some actually prefer a "raw" (i.e., distorted) sound (lots of electric guitar playing involves distortion, after all). Others want a correct -- or more correct -- part no matter what it sounds like.
I suspect that some of the latter group are collecting guitars that may be rarely or never played. Of course, as the owner of many radios and several TVs, I would never confess to owning any "shelf queens" that rarely get played :-)
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html