I think like you said if they sell 50 - 70 units, the units will start selling themselves just through the growing reputation.
However I believe it will take only a meager amount of sales, in the single digits, for the stock to take off. It's the show me factor. The revenues from each unit will be substantial, and start wow'ing people.
If only half of the distributors sold one unit in the first 12 months, I think the buzz will be loud and clear.
Surgical testimonials will spur more demand, and then VKNG's price per share should launch.