When I sell a bike on ebay I charge $25 for boxing, plus actual shipping, but per ebay's requirements, I state it in the ad listing. I think that is more than fair, as I spend at least an hour boxing a bike. Plus, someone local who doesn't need it shipped can pick it up and not pay the boxing and shipping. I think that people who want a bike boxed for nothing will get what they pay for.
Bob Freeman
Seattle