I think you and I have different bars for what “expensive” means.
Manufacturing things is expensive because of the fixed costs. To make it cheaper you need to make enough sets to dilute the fixed cost among N buyers. If at N=20 the price is already something people will pay, that’s not expensive IMO.
The problem is that the case doesn’t work that way, because the costs of machined aluminium are pretty much linear with N.
The fully machined aluminum case probably plays a part in there too.