How Much Does It Cost To Write A Proposal Letter . For example, $42.67 per hour by 5 hours is $213.35 for the project. You simply need to write the business proposal for your buyer to evaluate so you can begin the sales process. 25 Images Sample Letter Format For Business Proposal from shopforsanusvuepoint.blogspot.com Type in the date just below the recipients address. From, lenard solomon, kenknit company. You may also want to use a letter template to write a more descriptive summary of the proposal and include it as a cover letter.