Q. What is Minimum pricing?

The minimum transfer price an internal seller would accept will depend on whether it has spare capacity to utilise or not.   

If spare capacity exists the relevant cost and therefore minimum price to a seller would be the variable (marginal) cost of production e.g. extra cost of making and selling one more unit.  Variable (marginal) cost would be the only cost considered by a seller because fixed overhead is normally unavoidable and would not change if supply did or did not take place. The variable (marginal) cost represents the absolute bare minimum transfer price to a seller, in circumstances of spare capacity, at this price, the seller would be indifferent but not out of pocket.  Marginal costing may also be appropriate when no intermediate market exists for the seller e.g.  Seller can only sell to an internal customer and no external customers are available.

If full capacity exists, the seller would have to turn away external customers and business will be lost if further internal supply were to take place.   Because of this dilemma the seller would normally want a minimum price at least equal to the external market price it would normally charge when selling to external customers, this is assuming there is no difference in the cost of supplying internal or external customers e.g. differences in packaging, delivery or marketing costs, in which case the price would normally be adjusted. 

The minimum transfer price for a seller at full capacity is generally the external market price, if for some reason the seller maybe discontinuing other products to supply internally, then the minimum price would be the variable (marginal) cost of production and the lost contribution from discontinuing other products for internal supply to take place e.g. the variable cost and contribution lost being the opportunity cost.