Standard tower cases can easily cost that (or more), perhaps partly driven by it increasingly only being gamers buying them (so you can charge more for RGB, funky angles, or also minimalism, etc.), but server stuff is often more expensive than a desktop counterpart would be, different market but also more specialised I suppose.

I paid almost £260 iirc for a 4U case with 16x3.5" hot swap bays, a few years ago, and that seemed like a great deal (without waiting for something used on eBay anyway). Now, I still haven't really made use of it... but that's on me.