Okla. Const. art. IX, § 45

Monopoly or destruction of competition - Discrimination prohibited. Until otherwise provided by law, no person, firm, association, or corporation engaged in the production, manufacture, distribution, or sale of any commodity of general use, shall, for the purpose of creating a monopoly or destroying competition in trade, discriminate between different persons, associations, or corporations, or different sections, communities or cities of the State, by selling such commodity at a lower rate in one section, community, or city than in another, after making due allowance for the difference, if any, in the grade, quantity, or quality, and in the actual cost of transportation from the point of production or manufacture.