An Illinois commercial real estate purchase and sale agreement contains the key terms and conditions of a commercial property transaction. A long form agreement for the purchase and sale of commercial real property in Illinois.Read about the legal terms and disclosures you must add to an Illinois real estate purchase agreement. Learn what required information you must include. Get a comprehensive understanding of Illinois real estate purchase and sale agreements with our indepth overview and free template. This form of purchase and sale agreement includes guidance for both purchasers and sellers in Illinois commercial real estate acquisition and sale transactions.