Let's decipher what you just said. You (in this case TSE) are applying a mark up formula. For the price you buy it for. Please shed some light on how you have zero control. You have a formula and you set the price, correct me if I'm wrong, which I'm not, this is 100% your control. What isn't your control is what the importer or manufacturer charges for their product. Unless they have a set retail price, which you haven't indicated given your use of a formula, then ultimately you determine the price you sell it for.