Doepfer

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 .