A sales agreement is an important legal document that contains all the agreedupon terms between the buyer and seller for the sale of the property. This document is a business purchase agreement between two entities.It details the sale of a business from the Seller to the Buyer. The Seller agrees to sell, and the Institution agrees to buy, the Collection for a total purchase price of ______ ("Purchase Price"). The Institution shall. An Agreement of Sale is a document that contains legally binding information in relation to the sale of a property real estate between a seller and buyer.