I am working on this VCO design on the last couple of weeks. My goal was to have a simple schematic with low count of components which are broadly available and not too expensive and 1V/oct tracking. This is what came out and I am actually very happy with the result.
The oscillator core is based on the schematic from the Jupiter 8 but with up-to-date components. I replaced the current sink by a simpler version and made it optional to use two matched transistors or one BC847BS. I built a few versions now with the BC847BS and tracking over the whole range of my Beststep Pro is very good.
So components per VCO are only a few bucks and I am currently working on a PCB layout with eight oscillators on it.
Feedback on this is very welcome!