Don't forget that a key component of any tube amplifier is the output transformers [except for OTL's, of course!] I know that there are people who search for these "classic" makes of vintage x-formers, much in the same way people search for vintage NOS tubes.
Can anything beat Vintage Amps for the $$$?
Restored Fisher, Scott, or Eico integrated amps can all be had for under $500. Do you think any new or used, tube or SS integrated amps can compete in this price range? Any opinions?