Gold Lions not vintage they are current production.
There are also several others.
Admittedly, nearly all of the current brands, that are not mentioned by Adama, are actually manufactured by the same companies as mentioned. For example the New Senor corp manufacturers tubes for ElectroHarmonix, Sovtek, Svetlana and makes the Mullard re-issues and Tungsol. Some of these are made at the same plants some are made at alternate plants with different tooling. For example the Sovtek and the Mullard re-issue do not use the same tooling and are not made at the same plant.
In other cases, Gold Lion/Pm Tubes, Groove tubes, Ruby Tubes, Northern Electric, Psvane .... these are all tubes manufactured by the mentioned firms or by the Chinese firms but they all pass a bunch for tests to select for noise, microphonics, gain, etc. So, often, the consistence is better than just buying straight standard issue from the manufacturer.
What i am trying to say is that there are many options in the 6DJ8/6922/7308 family to choose from if we want a drop for one of them.
Unfortunately this is not possible unless we're talking about Electro-Harmonix, Sovtek, Ei or JJ tubes. Even then I'm not sure whether it would be possible. Those are the only brands which are still being manufactured.
All the other tube manufacturers have ceased production and therefore there is a finite amount of vintage 6DJ8 series vacuum tubes left of the planet.
Due to the laws of supply and demand all we would possibly be successful in doing is raising the price for all future buyers of vintage 6DJ8 tubes. Therefore, the only companies that could possibly be approached for a group buy are the ones listed above. Anything from Telefunken, Amperex, Siemens, Sylvania etc. are vintage and have a stable valuation which cannot be changed via mass purchases.