I recently found at work an old tape containing the first 7 minutes of a 1991 episode of "The $40,000 Chain Reaction". This particular version was hosted by Geoff Edwards, taped in Montreal, Quebec, and was made by Bob Stewart Productions.
The picture and sound quality are both excellent considering the age of the original tape it was recorded on.
Here's the closing for a 1989 installment of "The MacNeil/Lehrer Newshour".
I don't know the exact date but it's probably between March 27 and April 5.
Here are a few commercials that aired on ABC in the early 1970s. The ads seen in this 16mm color film excerpt are for Socialites Shoes, Serta Mattresses, Shake 'N' Bake, and Pristeen Deodorant.
This is all I have of a 1998-ish episode of "The Price is Right". If anyone has the date for which these three people participated in the Showcase Showdown, let me know.