A bit off point perhaps, but one reason I let my FFL go was the increasing cost of shipping. 90% of my sales were online and during the 3 years I had my license I saw shipping costs increase so much that merely listing a shipping amount that would cover it, was enough to scare potential buyers away. At first I used a local shipper, when they became too expensive I made the 50 mile drive to the nearest FedEx hub. The last firearm I sold online was as an individual after I was no longer licensed, it was a long gun and the cost wasn't too terribly bad, but it wasn't good either.
Things being as they are, unless you're selling something expensive enough to make it worthwhile, I would try and sell at a gun show rather than online. I don't have anything I plan on parting with at the moment, but if I did that's what I would do, even though most of the gun shows I have attended weren't overflowing with good offers from the vendors.