Parties: the "SELLER," agrees to sell and. , the "BUYER," agrees to buy, the premises described in paragraph 2 on the terms set forth below.A purchase and sale agreement is a contract between a buyer and seller for transacting a property in exchange for a specific price. CocoSign provides a free Massachusetts purchase and sale agreement template that you can download, edit, and use. A Massachusetts purchase agreement is the standard legal form for selling or purchasing a home. It documents the transaction's stipulations. Step 1 – Fill Out the Buyer and Seller Information. 1. Seller.