A letter is a couple of millimetres. Even a booklet should go Large Letter if not Small Packet. EBay encourages us to quote very low or free postage: they make money even if we don't. You should also charge for a Tracked method. If something isn't worth anything,  isn't worth paying for Tracked postage, don't bother selling it, bin it. We're wasting our lives listing stuff that doesn't even bring the minimum wage per hour for the hours spent dealing with it.