From most record shops.
I started with music in the early 80s. I bought LPs, and copied them straight to cassette, to prevent wear.
Now most of the albums I bought between 80 and 90 sound remarkably flat, lifeless, and dull. Could it be that the stores I frequented (stores which are not exactly in London or Manhattan) only got access to pressings off nearly-worn stampers? I do hope you know that in this era stampers often were pushed 1000s beyond their sell-by dates?
The point I want to make is that with LP there is no absolute reference disc. At least not one you can buy with any certainty.