I know this is only semi-related but I don't think spending a ton of money on NOS tubes is necessary for the amp to sound good.
I was fooling around with the gain tubes in my MPX3 recently and I was shocked on how good the ElectroHarmonix 6SN7 sounded. To my ears the EH sounded better than the highly regarded Ken-Rad VT-231 and was only bested by Sylvania VT-231. I wish they had a touch more warmth in the midrange but I was really impressed with the clean, natural sounding treble and a punchy bass. The EH 6SN7 ranks up with the SED EL34 as my favorite current production tube.