I’ve got a stack of lightly used CONN 12AU7’s and a smattering of NOS tubes, I just havent gotten that bug yet. Its an expensive bug 
Actually, I did buy a few lots on eBay looking for that diamond in the rough, but pretty much ended up with boxes of non-amp usable NOS tubes.
I do however, own a LaChapell audio mic preamp that has 8 12AX7s in it all of which are Brimars and Mullards. Like a buried treasure