You can enter your shipping supplies for your eBay business as a miscellaneous expense with a description of "Shipping Supplies"
Here's how to do this in TurboTax Online:
- Navigate to Federal > Wages & Income > Self-employment income and expenses
- Select or create your eBay business
- Choose "Add expenses for this work"
- Select "Other miscellaneous expenses"
- In the list of expenses, "Other miscellaneous expenses" will now appear.
- Choose the pencil icon to add your description and the amount
Alternatively, you could also consider these "Office Expenses" and skip the step of entering a description.