Demand is a function of price. Prices for a good or service only go down reliably as a result of decreases in demand if supply is constant. If supply isn't constant, then the change in price is a function of the fixed versus variable costs of production, and the price elasticity of demand for the product. If fixed costs dominate the equation, prices will go down so producers can recoup their capital investment; on the other hand, if variable costs dominate the equation and the price elasticity of demand for the product is low, the price may not change, or may even increase.