I think you’ll find body soap (body wash) doesn’t cost very much. I did some cost analysis after 3 full months of hosting (Thread posed about it here.)
My listing was for up to 10 people (reduced now to 8 people), with an average between 5 and 6 people per night and liquid body wash costs me only US$0.18 per night booked. I buy Olay brand which isn’t even close to being the cheapest. I don’t know anything about your listing, but I can guarantee the increase in price to cover the cost is very small.