I spoke with a friend today who is exploring an entrepreneurial pursuit.  As we discussed the business plan concept I eventually couldn’t help myself but to start drilling in on the economics.   So I asked the important question of how many units needed to be sold to replace this person’s current salary?   This is a useful question to determine if the business model is initially viable.  If you need to sell 10,000 units and only have the capacity to produce 500 per month you immediately can find the curbs in the business.