Scarcity value is an economic factor describing the increase in an item's relative price by a low supply.
[1] In terms of partial-equilibrium supply and demand, the markets where prices are "cost-determined" have a supply curve that is very elastic or even horizontal, so that an increase in demand raises the quantity of production much more than the price.
The seller of the product receives a price higher than the cost of producing the item and so receives a significant scarcity rent or producer's surplus when demand is high.
Note that the cost of production may be close to zero, as with a rare stamp, so that the entire price consists of scarcity rent.
He had discovered a great law of human action, without knowing it – namely, that in order to make a man or a boy covet a thing, it is only necessary to make the thing difficult to attain."