As used in this part, unless the context otherwise specifically requires:

(a) The terms Act, regulation or regulations, consumer commodity, package, label, person, commerce, principal display panel, and random package have the same meaning as those terms are defined under part 500 of this chapter.

(b) The term packager and labeler means any person engaged in the packaging or labeling of any consumer commodity for distribution in commerce or any person, other than a common carrier for hire, a contract carrier for hire, or a freight forwarder for hire, engaged in the distribution in commerce of any packaged or labeled consumer commodity; except persons engaged in business as wholesale or retail distributors of consumer commodities are not included unless such persons (1) are engaged in the packaging or labeling of such commodities, or (2) prescribe or specify by any means the manner in which such commodities are packaged or labeled.

(c) The terms ordinary and customary and regular when used with the term price means the price at which a consumer commodity has been openly and actively sold in the most recent and regular course of business in a particular market or trade area for a reasonably substantial period of time, i.e., a 30-day period. For consumer commodities which fluctuate in price, the ordinary and customary price shall be the lowest price at which any substantial sales were made during the aforesaid 30-day period.