Ah, the Sennheiser VSM201. Just a $30K vocoder. Seems like it was $25K when it released in 1977, but also didn't get to sell even 50 units, so quite rare. I guess you can get similar results with cheaper hardware, but if you have money and you have it around... ¯\_(ツ)_/¯
The article says that Daft Punk rented it. I was surprised about how much better the Sennheiser sounds compared to the others. From the audio comparison in the first YouTube video. I did expect minor variations in the harmonics but the differences are quite significant between the models. The other vocoder that sound almost as good is quite new and it seems to still be a prototype with a "contact us" price.
I can’t speak on Dromedary Modular’s behalf and I think rising parts costs have been an issue, but buying an Ultimate VoIS should be a fair bit cheaper than the Moog vocoder.