Their "research that found none like it" presumably did not involve an internet connection. That's where I found some in about ninety seconds. It seems you're lucky they have a phone.
It's on the small side at 34mm, but a lot cheaper than the Tri-Compax: from what I can find, it's around from about 2000 Euros upwards - late 1940s, apparently.
Tis a good thing that I cam here first and not there, rely on the TWAT brethren.
Could you PM me where you're looking?
You may be interested to know that they're asking GB£4650, needless to say that didn't get me to change the plans for the family to go back!