The price difference of most tube amplifiers has more to do with power supply, voltage regulation and output transformer quality than what type of tubes they use. Tube rolling is basically a tweak; so I doubt you're going to turn a $200 amp into a $1000 amp with just tubes. Also remember that amps made in China are much cheaper than elsewhere so the quality comparison shouldn't be readily assumed by a labor rate differential.
Can excellent tubes transcend modest amps?
I am wondering how far a good but not amazing amp design with decent parts such as Antique Sound Lab AQ1003 DT or a Jolida 302B can be improved by putting top notch NOS tubes? In other words, is it worth buying a used $500 integrated and give it an extreme tube make over for $200-400 rather than buying say a PrimaLuna or Cayin in the $800-900 range with its stock tubes?