anything that can be sent by mail is waaay cheaper than UPS or FedEx - the CDN post office charges a flat $5 for brokerage, and there should never be any customs duty on parts for vehicles over 25 years old, and certainly not used parts
also, the Canadian suppliers [Scotts Super trucks and the Old Car Centre, among others] can get most of the repro stuff for as good a price as ordering from US suppliers
Bill