Hi,
You could create a custom field of the table "item" and of the type "single dropdown". As values you would enter the price in the "value" input field and the text you want to appear in the dropdown in the "title" input field.
Then, with the price calculations plugin (
www.hikashop.com/marketplace/product/148...ce-calculations.html
) you could add the formula {xxx}/{quantity} where xxx is the column name of the custom field. That way, the amount added to the unit price of the product will be divided by the quantity of the product in the cart so that when the unit price of the product is mutliplied by the quantity, it will basically always result in the same amount added to the product regardless of the quantity of the product in the cart.