Send a For Sale By Owner prospecting letter to neighbors in 3 simple steps. Learn how to generate leads for your FSBO campaign.An Illinois purchase agreement is a standard contract for selling real estate from one party to another. Illinois Free Letter of Intent ( LOI ) Template. Utilize our Letter of Intent to formally express your desire to buy a product or service. Address. City. State. Zip. County. Permanent Index Number(s) of Real Estate: ______-______-______-______. The Real Estate is vacant and unimproved. Focus on three things: State your intentions, show that you have the financial means to make the purchase and make a personal appeal to the seller. Purchase and Sale Agreement. A purchase and sale agreement is a contract between a buyer and seller for transacting a property in exchange for a specific price.