Yes. Plenty of vintage tubes stored away in cabinets, and using all new re-issue tubes now and past few years. I rotate the vintage tubes in/out once in a while, just to make it seem like they are all worth keeping, and from some of the best vintage tube sellers & testing, yet not finding much of a need for them as much any more. Just buy quality tubes that are well tested with a warranty and helpful tube seller and you should be good. If you can do both types, great, if not, its not as big of a deal that some like to make it out to be imo.Best of Luck.
Would you buy a tube amp if you were unable to use vintage tubes in it ?
Not available or too expensive.
Hmm.., I don't think I have a definitive answer for myself, but I would do my best to avoid such amps. There is no substitute for great tubes, I guess, especially if you value sophisticated sound.