This is true! I am lucky My Sansui was sold to me near 100 bucks...But the price you described is way too much paid...I live in a marginal market , lucky me...
Totally agree its too much,but it is what it is...like anything vintage(cars for example) they were made better and to last forever back then,and each day there are fewer and fewer available,and theres no more being made...so its supply and demand.
TBH if I had cash to toss around I'd def drop big $ on one of the big monsters...that Technics weighs 91 lbs and a conservative 330WPC!!!!