Its safe to bet that any reasonably priced modern amp is built like total dogshit. Or, more likely, its that what we think is "reasonable" is not really reasonable. This 1972 Marshall price sheet has a 1987 head at $400 ($3000 in today dollars):

This 1976 Hiwatt listing has a 50W at about the same ($3K) in today's dollars:
Those are pricey imports, but even a Bassman head in 1976 is $1650 in today's money:

