Thank you!
Well, if you’re looking at building something like this, Zu is using some eminence drivers, based off of their beta10CX woofer. Almost 20 years ago, I used to work for a kit speaker and subwoofer design company in Seattle called Adire Audio and we made a kit with the Beta10CX and Eminence APT-50 tweeter that is documented here and can be made for a couple hundred dollars each.
A newer/slightly better version of this is available at diysoundgroup.com as the Volt-10.
However, I don’t generally recommend these coaxes as there is a large mismatch in the horn flare between the pole piece and the cone and this causes a lot of diffraction and response errors. The B&C coaxes are certainly better (and a lot more expensive) but I think a separate horn/waveguide is the way to go for more hifi applications unless you put a ton of work into optimizing things (like KEF has for 30 years).
As a company, if we offered something like this, it would certainly have to be at a higher price point than a kit, as we’d need to offer higher performance and you’re paying for the enclosure/furniture aspect of things and enough profit to support it and keep the lights on. Still, I think that more cost effective products are exciting engineering challenges, as engineering at it’s heart is doing the most with the least.