Cal. Bus. & Prof. Code § 12512

When the sale of any commodity is based upon a quantity representation either furnished by the purchaser or obtained through the use of equipment supplied by the purchaser, the purchaser shall in no case buy the commodity according to any quantity which is less than the true quantity of the commodity or compute the purchase price of the commodity according to a price per unit of measure that is less than the highest applicable price per unit of measure that is represented by the purchaser to the seller for the commodity, or, where applicable, less than a price per unit that is established by law, in statute, or by regulation. Violation of this section is a misdemeanor.