An attorney's explanation of an Office Purchase and Sales Agreement and its free template for commercial real estate. 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.This Standard Document is a long form agreement for the purchase and sale of commercial real property favoring the seller. Use a commercial real estate purchase agreement to secure transactions and protect your interests effectively. The following is a checklist of helpful hints for consumers to help avoid some of the pitfalls of purchasing a new or used home, or raw, undeveloped land.