I don’t think that you should have much of a problem finding 6922s or 6DJ8s. I see that Cary Audio is selling Amperex Bugle Boys 6DJ8s for $80 each.
(On edit: I am not affiliated w/ Cary Audio except as a past customer.)
https://www.caryaudio.com/vacuum-tubes-and-accessories/
Another option (which I now see was already mentioned by @dekay ) that someone turned me on to a couple of years ago that you might consider is the Voskhod 6N23. It’s a Soviet era tube; I am actually running a couple in the front of my 6922 Cary V12 right now.