They are out there. Most of these were collected with the last 2-3 years.

The beautiful necklace is from Jan Skipper AKA mosquitobay

Most of the small ones are from a variety of ebay sellers.

The rest are from online auctions or me buying directly from someone I met online.

When I had my store back in the 1990's I use to see on a regular basis full stands of these. In comparison to yellow jacket chevrons which are more common I probable saw one full strand of black for every 25-30 yellow jackets from the traders.
I think the main reason you don't see more it that they were just not popular within the trade itself so less were produced and traded.

Does this make them rare\valuable? It all depends on the buyer.