When studying economics we look at supply and demand. when the price and quantity are right, supply ans demand reach an equilibrium point price and quantity are effected by the producer and consumer. the producer can only sell their product at a price the consumer is willing to pay.
when there are lots of products(high supply) the price is driven down, when there are fewer products(collectables)and demand is high the price is driven up.
this is a graph explining the supply and demand.