Duty is on import, typically, and while ebay's global shipping program prepays the duty as part of the initial shipping cost, other shipping methods do not, and the duty can be assessed upon arrival to the country.
The important thing is that the rule is for the country importing the equipment, so the rules generally don't have to do with the shipper and should be consistent across anything you import.
Somehow got the origin confused.... yeah I think the US limit is something like $800 officially, but I have yet to be assessed import duty on like half a dozen shipments declared over that threshold. I think it's rare for an individual to be assessed, but possible.