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Cost price. This field is useful if the original price of the product changes simply because this is a combination.
Specific prices. Managing : Managing Quantity Discounts.
You can change the total price of the product depending on the quantity of products your customer buys, the user group, the country, etc. This is done with the "Specific prices" section of the "Prices" tab. Click on the "Add a new specific price" button to reveal the creation form.
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