Be aware that everything built today and in the last 20 years or so
(not counting something not a conventional keyboard like a TKB)
is actually a MIDI keyboard with a CV converter mounted inside.
This is true of the Analogue Systems and the Synhesizers.com
units, post-MIDI era monosynths, etc..

Considering that, you too could attempt to retrofit a converter into
a pleasing MIDI keyboard or just live with an outboard converter.

A lead I've mentioned in Analogue Heaven before but never
heard back from anyone following up on is back about 5 years
ago a shop in NYC, Two Lines Music in Manhattan (which was
called Dr. Sound back then) had many NOS units of Roland's 3
models of CV keyboards for the System 100M selling $300-ish
give or take for the different models. I have no idea if they still
have them but then they had quite a few units and they didn't
seem to be exactly flying out of the door (they've been trying to
sell an Emu modular too for well over a decade.) Sorry I don't
have their contact info handy .