[caconym_]

The people buying Mini-ITX cases for custom PC builds are typically hobbyists, and the value they derive from these cases (which are expensive across the board, it's a niche low-volume market) is not the same value you or I get from buying a (relatively) cheap ATX tower and throwing whatever parts into it. If you go looking for "similar products", I guarantee that you will find some very expensive cases indeed.

Not every product is for every consumer. This case is already sold out, so apparently somebody wants it.

[Hamuko]

My Phanteks Evolv Shift Air 2 mini-ITX case was about 120 € (with one 140 mm fan) and I don't think it was that expensive. And it looks really nice + fits beefier components.

[caconym_]

The Evolv Shift Air 2 is a cool case, but (as you say) it is on the large side for Mini-ITX cases and therefore likely has much more mass appeal, since the smaller a case is the more difficult (and rewarding for hobbyists/enthusiasts) it will be to spec out components that fit and have adequate cooling.

Just comparing it to some other popular Mini-ITX cases, 23 liters for the Evolv Shift Air 2 is nearly twice the volume of the NZXT H1 (13 liters), and far in excess of the Dan 4 (7 liters) or the Velka 5 (5 liters). Especially the latter two cases are extremely challenging to build in, and at 8.5 liters the "computer-1" is arguably most comparable to that segment despite its GPU length limitations. It's not a put-whatever-you-want-in-it case, and that makes it a niche offering.

I'm not going to argue that there's no TE tax attached here, especially since (unlike similar cases) it doesn't include a PCIe riser or other electronic components, but it's not way out of range for its market segment.