Sadly no vaporizer company has really publicly released sales data figures.
The only data I do know is that Pax originally claimed they had sold over 1 million copies of the Pax1 vaporizer, but that was a claim made 3+ years ago (back when they were selling the Pax1 vaporizer in America only), before they started selling the pax2 and pax3 vaporizers globally, so I really don't know how many millions of copies they have sold.
Meanwhile lesser known vaporizers (Such as ones with a Zippo like appearance) will only sell a few thousand copies over it's entire lifetime before production was discontinued (source: private conversation with someone close to the company).
Really wish I had more access to sales data, that would REALLY help make my life a lot easier when selecting the next vaporizer to build accessories for!