A coworker once sent me a picture of a Plinko chip someone had given him, asking me whether I thought it was authentic. I replied that I couldn't be certain, but I did know that the actual Plinko chips used on the show are kept in a locked container, and there are only ten of them. In the end, we concluded that while his chip looked real, it was possible it came from the live show.
This eBay listing is light on details, but the lack of wear and tear visible in the pictures leads me to believe these weren't used on the show. I know the props folks made some lookalike chips for photo shoots, which would be easier to "lose track of"... I wonder whether that's what those are.
Meanwhile, when I checked out that listing, the algorithm suggested a listing for an
animation cel from the opening to 1979's
Beat the Clock, which seems more likely to be authentic.