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

Like others have said, I wouldn't have patience with a tube amp that demanded NOS tubes to sound good.  There are plenty of good new tubes on the market today.  My Williamson amps sound great with Gold Lion KT66's and GZ34s, and Tung-Sol 6SN7s.

@wmr57- my doppelgänger--you still using the Allnic phono pre? I rolled a bunch of rectifiers in that, finding the sweetspot for me, given my system voicing, to be the GEC U-52 cup base. I have a metal base Mullard (really a Philips-Miniwatt from Holland), a grail tube, but it had mucho bass and no "air" or nuance on top. For those unfamiliar with the unit, it is supplied with a cheap, crappy rectifier (or at least it was) and I suspect the manufacturer knew that folks were gonna roll it. It’s really the only tube that makes a difference in the unit.

@inna- with respect to Lamm, they supply a Sovtek 12ax7 as part of the full tube complement for the ML2 series SET amps when you buy from the company, which most do. Those usually get rolled by owners. I asked Lamm about it once- they didn’t really go to the trouble to source NOS 12ax7s  (though a lot of the tubes in the amp aren’t new manufacture--you take your chances on the power tube/regulator Russian 6C33C which you can buy cheaply in the open market but there are risks of failure and those tubes have a weird range of bias that corresponds to each amps range for biasing them, a factor that Lamm keeps proprietary). The only tube I "roll" in the Lamms is the 12Ax7 and use an old stock ribbed Tele, which gives the amp a little more bite than the smooth plate. Both versions of the Tele sound far better than the Sovtek. 

As to wide availability of common tubes, like the 12AX7, you can buy "pulls" of that tube all day that measure well. My experience is that they don’t last as long and go noisy. True NOS isn’t cheap if you can trust the vendor and my experience is that the amps hold bias better too. (Use a Fluke pretty much every time I run the amps to verify). 

In a world where tubes were common and easy to get it was fun. Now that a lot of these are unobtanium--try finding NIB GEC KT66s as a quad (I did some years ago for my Quad II amps), it becomes another hurdle. I’m not in this for bragging rights, I’m in it for sound, which is why I suggested that modern tube amps that will sound good using readily available modern production makes even more sense today, with the depletion of stock. 

I run a combo of NOS vintage tubes and new reissue tubes. It depends on where and how they are in the circuit. Personally, i think that in many cases, one gets possibly a more reliable tube with some of the reissues. Simply because the NOS tubes, like the 50's and 60's tele's etc are really unknown as to their usage. I can't say how many times i have bought NOS 'vintage' tubes only to look at the tube pins and to know that this tube is more than just used. Do NOS vintage tubes sound better than the current reissues? In most cases, i would say they do, but again, depending on where in the circuit. 

Today, I also think that some of the new power tubes are superior to the power tubes of yesterday, certainly in SQ, maybe also in reliability. ( although that depends greatly from tube to tube). 

Would I discount a good piece of tube gear if I could not use a 'vintage' tube in it...absolutely not.

I wouldn't, but I like equipment that is flexible as I gou through the adventure of finding my best sound. 

Soon there might be neither Chinese nor Russian new tubes available if the trade is stopped, so you better get a supply of them. Not my problem, I stay with vintage. You see, there is an unexpected advantage, in addition to expected advantage.