A random sample of people are sampled from the pricing community.  They're asked what price they would pay for an item.  The prices and quantity of people that would pay those prices are graphed onto a linear regression model.  This model can be used as a demand curve.

A demand curve is used to calculate the expected profits a company will get at a price.  Although a lot of math goes into this calculation, your friends at Leslie's Pricing Community have you covered.

Leslie's Pricing Community is flexible.  We can always just do a twitter poll asking people what they would pay for an item.