It’s irrelevant how much you charge your buyer for postage… free, exact amount, more than exact amount, less than exact amount: you’ll still be charged by eBay for the postage label if you purchase through eBay.
Or…
You’ll pay the Post Office directly if you don’t buy the label through eBay but go in person to the PO. (If you have MyPost Business, you are likely to be paying less than through eBay, and in any event eBay don’t charge less than it costs directly through AP.)
In other words, you can always print the shipping labels on eBay. Free postage means you’re not charging the buyer for the postage component; it doesn’t mean that the seller isn’t paying. (In case you weren’t sure about that…)
