An Arizona residential purchase agreement is a legal document outlining the terms and conditions for a buyer's purchase of residential property from a seller. Read the purchase contract carefully.Note where the builder or developer is placing earnest money (ie. Ensure your offer is complete and spells out in clear, concise language the terms and closing costs. Arizona Residential Purchase Contract is a legal document that outlines the duties, requirements, and other information when buying a house in Arizona. This particular contract dictates the purchase and sale of real estate in Phoenix and throughout the state. A For Sale By Owner contract Arizona must include: 1. The Purchase Price, 2.