A purchase and sale agreement is a contract between a buyer and seller for transacting a property in exchange for a specific price. To help you prepare the paperwork for selling a house without a realtor, here is a list of 12 musthave documents.A real estate contract is a legally binding document between two or more parties participating in a purchase and sale, exchange or transfer of real estate. A Utah residential purchase agreement is a contract used when a buyer makes an offer to purchase real estate from a willing seller.