Interpretation or definition of "shadow prices" I do understand that shadow price associated to a resource is the marginal profit you would get if you buy one more unit of that resource. I also know that it is the minimum profit you would accept to make if you're selling your resource. What I am confused about if shadow price is what you're willing to pay for one more unit of the resource in addition to the market price or is it exactly what you're willing to pay?
 A: The shadow price is the price, which you are maximal willing to pay for one additional unit. The shadow arice of restriction (i) of the primal problem can be calculated by solving the dual problem. The corresponding optimal value of the dual problem is the shadow price. 
If the shadow price is $\lambda _i$ and you raise the bound ($b_i$) by 1 unit, then the optimal value raises by $\lambda _i$.
A: The 'shadow price' is of importance in non-market valuation. 
For example, in a market economy goods are denoted in terms of price. Subsequently, we can determine the marginal rate of substitution between two goods, and therefore how much an individual/group of individuals value something relative to something else. 
However, as you'll know, the domain of economics is typically quite broad, and applied to the environment and health etc. 
Often environmental and health benefits have no market price. It follows that in constraned optimasation problems, the shadow price is the value that should be attached to that under optimising conditions. 
