This Agreement constitutes a sale of certain assets of Seller only and is not a sale of any stock in any entity comprising of all or any part of the Seller. A business sale agreement is a legal document that describes and records the price and other details when a business owner sells the business.Once you have a general agreement with the buyer, the buyer usually drafts and signs a non-binding letter of intent. The documents you need to buy or sell a business depend on the structure (discussed here) and complexity of the deal as well as its specific terms. Purchase and Sale of Assets. Asset Purchase Agreements (APAs) are essential documents for asset sales, but they're far more complex than a simple transaction.