Transaction value governs excise valuation; related party relationships and prescribed rules determine non transaction cases. Valuation for excise duty uses transaction value where the assessee sells at removal to a non related buyer and price is sole consideration, the transaction value being the price actually paid or payable including buyer liabilities connected to the sale (such as advertising, marketing, storage, handling, servicing, warranty, commission) but excluding excise, sales tax and other taxes; otherwise valuation is as prescribed, and goods with a fixed tariff value are excluded.