Not quite - The B7971 was specially made in a limited run - just a few 1000s in total - and we know that the last cache known to exist of those was dispersed a few years ago - several members here bought significant caches - I know of at least two in the UK and more elsewhere of 100s of tubes each - as far as we know, that's it for 7971s - they were sold off for between USD 15 and USD 25 each - the guy who found them was a coin dealer and didn't really want them.
Z568xs, OTOH, were a commodity tube and used all over the place, so I suspect that there ar probably 10s of 1000s left, but because they're hidden away and drip-fed onto the market, the price is held high.
Part of the reason that I'm now doing neon & scientific glassware (like Alek, Dalibor and probably several others), is because this cosy cartel of suppliers needs to have competition.
Nick