Those amps were "expensive" because they were made in USA, with USA salaries and USA made parts.
Ok, Leo relied a lot on Mexican workers, but I guess they were not "illegal" and must have received a maybe smaller salary (70 % ?) but that does not account for the huge difference.
And modern parts are made by the millions, in high speed automatic factories, and for an excellent price.
But in any case, real cost of things should be measured in "work time needed to buy them"
If a Champ costs $500 today and your salary is $4000 as a car factory worker, it cost 1/2 week.
If car factories close and you earn U$2000 at Mc D or Wal Mart, a $250 Champ still costs 1/2 week.
Just a simplified example, with made up salaries nicely divisible by 500 to show that "the number printed on a green back paper" does not tell the whole Truth.