High grade cards in the 70's-mid 80's.

[goudey1933]

I have very fond memories from this time period for myself from early teens buying my 1st T206 continuing into the early 80's ...my college years with Goudey cards.So when the veteran collectors talk here on the forum of the gold old days it brings back many pleasant memories.
So this will be my 1st question of a few directed to the those who collected during the days before auction houses and graded cards.This question arose as I looked over the new REA catalog.Just an amazing amount of high grade prewar cards....not to mention postwar 50's.
The question is during the said time period did the collectors have the opportunity to buy cards like those at shows or through the mail.This may seem like a silly question but where did all these high condition cards come from?Did the advent of big money bring them out of collections?I know there have been and continue to be "finds" to add to the numbers.Also what was the collectors mindset towards cards such as these when come upon?
I look forward to going back in time with your input.
Scott