The demand is not subjective and it's so much higher for vintage tubes. That alone speaks volumes. It took me three months of constant bidding on ebay to collect four WE396A at an affordable price that wasn't all that affordable.

I have an older relative who was a tube engineer in the late 1950's. I wish I could get him to share some of his knowledge and experiences working at Western Electric from back in the day.

The Psvane probably sounds good as do JJ gold pins but I doubt you'll see folks selling off their NOS Mullards to buy a sleeve.