As far as I can tell, the common tubes are available you can get a quad of JJ KT 77s for $131 on Amazon today.
Tubes becoming hard to get?
An article in today’s WSJ talks about tubes for both guitar amps and stereo gear becoming scarce due to Far East and Ukraine/Russian tensions saying most tubes originate from China, Slovakia, & Russia. As such, people are beginning to Hoard and retailers are beginning to limit purchases.