A business purchase agreement marks the official start to the sale of a business. Read our blog to better understand each part of this important document.Identify the parties involved in the transaction. 2. Learn the fundamentals of creating a business purchase agreement including the roles, expectations, and timeline. Be reasonable, draft a winwin agreement, and include the most critical clauses protecting both parties' interests. A business sale agreement is a legal document that describes and records the price and other details when a business owner sells the business. When it comes to filling out a real estate purchase agreement, several key players are involved: buyers, sellers, real estate agents, and attorneys.