"... the price of BMWs during the 1980s. In the 1970s and earlier they used ot cost about the same as a Buick"
1970s and earlier BMW NA was not even in play. But that aside, drive a 1980s Buick and a BMW 3 series of the same era - 320i, back to back and you'll see why their prices has risen steadily since. Poor example at many levels. I have a number of friends and relatives that have uber expensive audio/video systems and they know their gear inside out and almost always shopped for best prices.