翻译一小段话，希望意思表达准确，谢谢！中译英

I would like to know the formula for calculating selletion cost (calculation method), In addition, the unit price of our production is low ( ** yuan per unit), the profit is very limited, could you reduce the selection cost? thank you!

I want to know the formula for calculating the cost of selection. In addition, our sigle price is low (Formula for calculating the cost of selection (calculated), In addition, our low unit (**per). Since the profit is very limited, can you reduce the fee of selection ? Thank you very much!

May I know the Formula of the cost of computing for selection ( the method of calculation ), in addition, our products are priced lower (** /pcs), profit is very limited,Can you reduce the selection of the appropriate fees? thank you!