Purchase and Sale Agreement. A purchase and sale agreement is a contract between a buyer and seller for transacting a property in exchange for a specific price.A Texas residential purchase agreement outlines the terms and conditions of an offer to purchase real estate. I'm gonna break down all the terms and conditions so you can understand what it means and we're gonna fill that out so you can have a real-life example of it. Get a comprehensive understanding of Texas real estate purchase and sale agreements with our indepth overview and free template. Step 1 – Fill Out the Buyer and Seller Information. 1. Seller. Write down the seller's full name. 1. Identify the buyer and seller in the agreement.