The additional cost field is for other product-related costs (i.e. inbound shipping fee) when configuring the Min & Max Price and Your Price.

To apply the Additional Cost to multiple listings simultaneously, utilize the Bulk Action feature. The added additional cost will reflect in the profit calculator of the selected listing(s).

• To set up the Cost for multiple listings, please select the listings you want to set the additional cost to. Following that, visit the “Manage Listings” page and then click on “Bulk Actions > Set Cost & VAT”.

• In the pop-up screen, locate the “Set Additional Cost = ___.” 
• Toggle the On/Off button to turn on or off the setting.