Use a California business purchase agreement to record the sale of a business. Download your free template today.Here's a step-by-step on creating a business purchase agreement with a free business purchase agreement template. This guide will help you understand how to fill out and sign a business purchase agreement template so that everyone's best interests are protected. The easiest way to create a Business Purchase Agreement is to use a template that is customized to your state. A business purchase agreement is a legal document used to set the terms and conditions of a business sale between a buyer and a seller. Get the terms in writing when buying a business.