An Illinois boat bill of sale records the purchase and sale of a vessel between a private seller and buyer. Copy of Bill of Sale or Purchase Agreement; Check or money order payable to Dept of Revenue for tax amount due.An Illinois boat bill of sale is a form that transfers a boat from seller to buyer for an agreedupon price. Complete your Illinois bill of sale for selling a boat here. Our bills of sale meet the state requirements. Next, provide information about the boat, trailer, and engine. Transfer a boat's ownership with a seller warranty. Use our attorney-drafted boat bill of sale template to outline the terms and conditions clearly. A boat purchase agreement is a legally binding contract between two parties that establishes the terms and conditions governing the sale and purchase of a boat.