"Do I have to pay..."
That depends. If you filed a tax return that included schedule C for your self-employment business and schedule SE for self-employment tax, then you don't need to pay to amend. You will need to download a special amend-only version of Turbotax to install on your own computer since you can't file online. You will also need your as-amended tax data file, that you can download from Turbotax online.
If you did not include a schedule C originally, you will need to pay for Turbotax self-employed version, or at least pay the difference between whatever version you used and the self-employed version. You can call customer support to work that out.
Note that you can deduct ordinary and necessary business expenses. That certainly includes listing fees, shipping charges, and credit card processing fees. However, be careful how you reported your sales. For example, if you sell an item for $100 and you pay $10 in fees, you might book that as a sale with $100 price and $10 fees, or you might book it as a $90 sale. If you book it as a $90 sale, you can't deduct your fees since they were not included in your income. You must also be filing as a business--if you are treating your eBay sales as a hobby (and not filing schedule C) you can't deduct expenses from a hobby.
