In anyone is interested, Horst Miracle Probes are back in stock, at least available from
www.rv-partsplus.com
Apparently they are now being distributed by Valterra, and they were a bit delayed in the printing of the card that is part of the packaging. But the dealer I bought them from convinced the company to ship the probes with a print out of the card. So the ones I got lacked the packaging.
Was a bit expensive for shipping though. It was $12, but from Canada, so probably international rates applied.
It came to be rather expensive; $77 for a set of grey and black sensors plus shipping. But I now have a reprieve as I can put them in so I don't have to rush building an adapter like JamieGeek is doing.
Now I can take my time designing a new panel or adapter for a panel without feeling the need to rush it.