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. Complete and mail the Notice of Sale form.(attached to the bottom of the title) to the. 1. Enter the names and mailing addresses of the buyer and seller. The Illinois bill of sale form approves the exchange of a financial consideration for an item of property into a text register. Illinois bill of sale forms are documents that provide information about the sale, purchase, or trade of property.