Transfer pricing - Lost Contribution

I am having problem calculating the lost contribution while doing minimum transfer pricing. I know that (Minimum transfer pricing = Marginal cost + opportunity cost) where opportunity cost is lost contribution for the selling division. Please tell me how do i calculate lost contribution and in what perspective should i think as selling division or buying division?? And please also tell me the formula for maximum transfer pricing. Isn't lower of either: (External selling price - variable cost of buying division) or (External selling price of market) Correct me if this is correct.