Just FTR, Fairphone started with below 50k units, with a licensed but slightly changed model, and then designed and produced a mid-range phone with the aim to sell 120k units. And they developed an entire business architecture.
Fun fact: the FP2 was, AFAIK, the first phone sold with a modular concept, and since recently, you can upgrade your camera.
So, 50k is possible for a start-up with a good idea.
