"If a willing buyer pays you $50 for an item, it's FMV is $50. Goodwill has nothing to do with it."

Obviously, then, this results in an intentional a loss on every item. That means Hobby or Personal, not business. "I know it is costing me more to do this than to just giving it away." Yet, if you ask the person why they are doing it on eBay, they will tell you, "I thought I could make a bit of money back."

Sometimes you have to show them the reality. Let them see what it costs them personally, or let them see how to run it as business and pay taxes.