As I said, I can't really see why a consumer would want stand-off insulators for their own board. However, if they did, they would only have to Google for "ceramic standoff insulators" to find thousands - if they were for their own board, there obviously would be no reason why they would have to be identical to the various ones DNOs have used (over the decades) for their own boards.So, on the strength of that, it's perfectly reasonable that no-one will identify the stand off insulator and whether they are still available?
As RF has said, if you would but tell us what you're trying/wanting to do, we might be able to help you more specifically.
Kind Regards, John