Scarcity prices are determined mostly by the last units available. Imagine demand is just below supply: then very little of the price is driven by scarcity. Now imagine that demand is just above supply: it's not hard for prices to increase dramatically, because every item is being competitively bid on the price will increase until demand at that point is below supply again.

The only time you don't expect small improvement in supply to have an effect on price is when you're far from being supply limited.