1) Click on "Manage Inventory" under the 'Inventory' heading of the Control Panel.
2) Search for your item by it's Item ID (or Author / Title)
3) Scroll down to the 'Search Results' and click the 'Edit' link under your item.
4) Click on the 'Pricing' tab.
5) Next to 'Handling Fee ($):' Enter any extra shipping charges you would like calculated for this item. This amount will be added on top of standard shipping rates.
6) When you are finished editing your item's handling fee, scroll down and click the 'Save Changes' button to finalize.