Complete and mail the Notice of Sale form (attached to the bottom of the title) to the Secretary of State's office. ACCEPTANCE DATE: ("Acceptance Date").SELLER'S INFORMATION: Seller's Signature: Seller's Name (print):. A master purchase agreement is a legally binding contract between buyer and seller, and typically relates to buying and selling goods rather than services. A vehicle sales agreement is a lawful arrangement summarizing the terms and conditions of a vehicle sale between a customer and a seller. An Illinois motor vehicle bill of sale documents the purchase and sale of a motor vehicle between a private seller and buyer in the State of Illinois.