In Moscow, where you at the Ismailovsky outdoor market? I have occasionally found Nikkor Ai lenses there. There are a couple of very good stores for second hand cameras of all brands, that carry Soviet equipment, in Moscow. The prices were not unreasonable. Check out www.kamera.ru for example.

I found a camera store that carries used cameras in Kiev as well, not far from subway station Stadion. I looked at one old Russian folder and asked a few questions, but the lady that was attending the store that evening did not know anything about the camera. You might have better luck if you go there.

In both cities you can look for online ads from people who are selling their own used cameras. For this you need to know Russian or Ukrainian in most cases.