Would you buy a tube amp if you were unable to use vintage tubes in it ?

I think, Lamm ( Vladimir Shushurin ) built his amps around particular vintage Russian tubes. But you couldn't buy them from him unless you had Lamm.

12AX7 and 12AU7 vintage tubes are still plenty, probably enough for the next 50 years. As for vintage power tubes, yeah, that's increasingly a problem, both to find a matched quad and rising prices.

I should've bought Gryphon Diablo 120 instead of VAC Avatar SE, so much easier. No way.

I would use all new tubes if necessary. As it happens, I was able to get a pair of NOS military-grade RCA 6SL7 tubes for the drivers in a KT88 push-pull amp I have, which has made an improvement, as have also the higher grade PSVane power tubes.

Yes. In my 5 tube amps, I use many current production tubes. Not because I’m cheap. I have boxes of NOS in the closet. I just prefer some of the new tubes is some cases. In others, like 5ar4-type rectifiers, current tubes can’t match up to my favorite NOS. But plenty-good tubes are being made these days.

@mapman I think you're missing the point.  I believe that all the amps referenced sound great right from the start and don't rely on old tubes to sound good.  Tube rolling allows for adjusting the "house sound" to one's taste.  These aren't generally stratospheric changes, though.  My VAC Signature II's sounded good with the KT-88's they came with.  For me, they sound best to my ears with KT-170's.  I agree completely with Mulling-"Vintage tubes are great, but new tubes are better than no tubes".

Like @chenry, I have several matched quartets of NOS RCA and Sylvania 6SN7 tubes that really complete my desired sound-and each brand has its own flavor.