Value of supply through an agent: use market value or supplier's option tied to recipient's nonrelated sale; fallback rules apply. Value of supply between a principal and his agent is the open market value of the goods or, at the supplier's option, a valuation based on the recipient's non-related sale price of like kind and quality when intended for further supply; if not determinable under these methods, value is to be fixed by the alternative valuation rules in the prescribed order.