sjhCanadaFrom the FAQ:
". Most international packages are shipped via UPS Mail Innovations, which is a service where the parcel is first picked up by UPS, then passed on to USPS, taken to another country, and handed off to the local postal carrier. This method of shipping is actually cheaper than USPS by about 30% - which of course, we pass on to you! "
So, the tl;dr is: it goes through USPS. Theoretically, it should mean customs fees are low. You never know, though.
Either way, I ain't getting a Cherry MX Clear keyboard up here for this cheap.