1. have the US seller identify the exporter - the US government requires that this exporter be a Federal Firearms Licenced (FFL) gun dealer for most exports. In many cases the US seller is an FFL dealer.
2. apply to International Trade Canada (ITCan) for an International Import Certificate (IIC) by calling (613) 996-2387 or by faxing your request to (613) 996-9933 and requesting blank application forms. Once completed, the form should be returned to ITCan for processing and certification. Expect this process to take 2-3 weeks. The certified document will then be returned to the applicant for onward delivery to the US exporter. There is no charge for the IIC.
3. pre-register the firearm through the Canada Firearms Centre. Pre-registration allows the importer to clear the firearm through the Canada Border Service Agency without any undue delay.
4. the US exporter will attach their copy of the IIC to their application for an export licence. In the US, applications for shotguns are administered by the Department of Commerce and for all other firearms are administered by the Department of State.
5. once the US export licence is issued the US exporter may then send the firearm to Canada.
6. the Canadian importer is responsible for declaring the value of the firearm to Canada Customs and for ensuring that all safe storage and safe transportation regulations are observed.
7. within 30 days of arrival in Canada, the importer must have the firearm verified and such verification confirmed with the Canada Firearms Centre.
Questar offers the service for $750. But they handle everything on both sides. Daves Sport Shop (Sponsor) offers it for around $250 plus additional fees for multiple firearms, but they only handle things on the US Side, and will deliver the firearm to the border for an extra fee.