For purposes of this chapter, a manufacturer or producer to whom an article is sold or resold free of tax under for use by him in further manufacture shall be treated as the manufacturer or producer of such article.
(1) at the price for which the article was sold by him (or, where the tax is on his use of the article, at the price referred to in ); or
(2) if he so elects and establishes such price to the satisfaction of the Secretary—
if he so elects and establishes such price to the satisfaction of the Secretary—
(A) at the price for which the article was sold to him; or
(B) at the price for which the article was sold by the person who (without regard to subsection (a)) is the manufacturer, producer, or importer of such article.