As far as I know, you just put in the package dimension/weight and Ebay does the rest. After sale, you purchase a shipping label from them.
I've found that to the USA, it' about $13 CAD. However, across Canada the price varies based on location. To ship from Vancouver to the Maritimes, it's closer to $20. Sometimes those flat rate boxes from Canada Post are cheaper.
Ebay shipping includes tracking and $100 of insurance.