Well, look at Albinos in any breed.
20 years ago some of the albinos that are readily available today numbered in the single or double digits throughout the entire continent. So the demand far outstripped the quantity. As the numbers of offspring increased, and they became more common, the price dropped as people had more options to buy. It's the same with any market, be it oil, gold, or RAM.
RAM prices had been dropping steadily for years when the single largest producer of chips in Asia burned down in a fire. During their rebuild time, the amount of inventory in reserves dwindled rapidly and prices skyrocketed. Once the production was back, then prices dropped steadily once again.
It's all about supply and demand, and how much you need to sell in order to make a profit.