How expensive are best NOS tubes ? And how difficult to find ?


Phono stages, preamps and power amps. Any non-Chinese adequate substitutes? I know that if you have Lamm, Vladimir has a few sets of Russian tubes in stock for each particular unit, and it is not really expensive to retube them. But if you have, say, VAC or CAT or Atma-Sphere and want best longest lasting and most reliable tubes, what then ? Don't ask me why not Chinese, I can't talk about it here except that I don't trust their quality control.
inna
This is not about retubing what I have now, I don't have tube equipment, this is about possible future upgrades. I suppose, best tubes is a significant part of the cost, and I am talking high level components. Not interested in mid-level something tube equipment.
And NOS tubes are old stock, prices must be going up and availability down. Say, $15k - $20k used tube equipment could cost double that within ten years of ownership, or what ? Yes yes, it depends on particular equipment and tubes, hours of play and stand by, pure luck and maybe other things. Still, should cost a lot for an all tube system even if not the double.