great post @bluethinker
I run a lot of searches and have a pretty good idea.
I know what's hard to find that I looked for, and I also looked at each company's revenue to be able to weight things.
I didn't do a spreadsheet so these are my impressions:
Cambridge Audio, NAD, Rotel, Parasound, Bryston - lots of good deals
Jolida - lots of on the used market
Hegel - very rigid price-wise
Similar story for the speakers, Klipsch, JBL, older B&W models everywhere.