Any way to not add product price to total price of order

Is there a way to add a product to a order, but does not include it’s price in total sum of the order? In our company, customers buy us products in boxes that have for example 13kg of stuff in it, and they want to also know the price per kilogram. Calculating it manually takes a lot of time, and if I add a product “price per kg” to order, then the total sum of the order will be calculated wrongly.

Please did you manage to do this? or is it not doable?

Product composition (kit) doesn’t is valid for you?