The Geist from Geistmaschine ought to be one of the most expensive keyboards ever made. Even though I didn't spring for the deluxe version, I still ended up liking it quite a bit, although, I kinda wish I would have kept the money instead.
Geistmaschine Studio | ASP: https://geistmaschine.io/pages/asp
Geistmaschine ADA: https://geistmaschine.io/pages/ada-explore