When creating a new items set, we can set the set option. We use other elements to create the whole. There is a possibility to give an optional price for the option.
When you select an option in the home page, the standard price is calculated instead of the price of the option. in stores, the price is stated correctly.
In this example: the standard price is 64.99, when you choose 20 lamps x 0.40, the price should be 72.99 and not 109.59.