With our free Sales Agreement form, you'll be ready to print or download your contract in no time. A sales agreement is used to describe and track the exact details of quantity and cost of purchasing or selling goods, services, or real estate.The RPA is the foundation of every successful real estate transaction in the state of California. A purchase and sale agreement is a contract between a buyer and seller for transacting a property in exchange for a specific price. Your agreement needs to say that you both agree to end the marriage and what you agreed about property or spousal support.