The price of a product is determined by the demand and supply of the market.
Generally speaking, if supply held constant, the increase in demand will increase the Price of the product. e.g. the Price of HK housing.
On the other hand, if demand held constant, the decrease in supply will increase the Price of the product. For example, the price of Egg in HK, since there was posion in the egg from Mainland China, the supply of Egg from Mainland stopped, that the total no. of egg supplied decreased, finally, the price of the egg increased.