The cost of making something is only used to determine price floor (i.e. if perceived value is lower than the price floor it makes no sense to create this product).
What your model of perceived value isn't accounting for are speculators who are in a market with no real vested interest in the product. The correct amount of speculation within a market can round out extremes but there is a balance. Free markets generally find the best prices for most things and works well in the majority of situations.