In 1990, before analogue keyboards made their big comeback, sales of the first commercially-available MIDI to CV converter bottomed out, because everyone who needed one (and could afford one) had one.
I was sure I needed one, but couldn’t afford one. My girlfriend at the time, who was also interested in electronic music, made a deal with our Roland rep (we both worked at the piano store) and we bought three of these guys at a discount. When the invoice came through we were charged close to list price for them. It was a bit ugly at first, but it got worked out in the end. The other two were sold for food after I decided to get out of retail.
The processors in these units must be pretty slow, because if you don’t have a little portamento, or if you have an instantaneous attack, most notes will start with a high-pitched click that I’m guessing represents the pitch/voltage of the unit’s rest state.