A.R.S. § 34-202: Bids by contractors; estimates when work not done by contract

A. Proposals for construction of buildings or structures, or additions and alterations thereto, shall be accompanied by bids for all of the proposed work, signed by a responsible contractor and accompanied by a certified check, cashier's check, or surety bond.

B. If the proposed work is not to be done by contract, the accepted completed plans and specifications shall be estimated by a person specially qualified for that purpose and appointed by the agent for that purpose.