Ariz. Rev. Stat. § 34-243
In awarding contracts for furnishing materials to construct a building or structure, or additions to or alterations of existing buildings or structures, either directly or through a contractor, to any political subdivision of this state, to be paid for from public funds, the contract shall be awarded to bidders who furnish materials supplied by a dealer who is a resident of this state who has for not less than two successive years immediately prior to submitting the bid paid real or personal property taxes assessed under title 42 in preference to a competing bidder who furnishes materials not supplied by the resident dealer, whenever the bid of the competing bidder, quality and suitability considered, is less than five per cent lower than that of the resident dealer.
A.R.S. § 34-243