Revenue Law - Customs Duties - Paragraphs 8(1)(c) and 8(1)(d) of the Schedule to section 19 of the Customs Act - Whether there was a sale for export to engage the transaction value method - Whether the fallback method was the appropriate method of valuation - Whether fees paid post-importation were properly added to customs value of imported goods - Whether procedural errors by appellate tribunal determines appeal which is by way of rehearing