Just to quantify this a bit more: they plan to hit a rate of 500,000/year by the end of 2018, and so far the company has sold something like 200,000 cars total, ever, since it started.

(I don't know how likely they are to hit that goal by the end of 2018, but they're trying.)

That's a very lofty goal indeed. They will definitely have to come down in price

The Model 3 is supposed to start at $35,000. Demand doesn't seem to be a problem, as they have hundreds of thousands of reservations and pretty much stopped trying to solicit more while they work through the backlog. The major challenge for now is actually getting production up to capacity.