The easiest way, and not always the cheapest, is to buy from sellers using the Global Shipping Program. This shows you to cost of importing approximately before you bid.
Once you bid the program calculates your duty (to Canada) and tax (to your province - between 5% and 15%) and adds a $5 service fee for PitneyBowes .
OR you can ask before bidding if the seller is willing to ship by USPS/Canada Post. But, he does not have to agree to this. He may also want to use a Delivery Confirmed service which will cost $20 to $25 (although First Class International recently started tracking, worth mentioning to your seller). And of course, while Canada Post is lax about collecting duty, tax and their own $10 service charge, you still might be the one who is asked to pay.
The most important thing to know is that you should NEVER bid with a US seller who only will use a courier like UPS or FedEx. These companies have a terrible reputation for heavy 'doorstep' charges and hurt US sellers because the companies do not inform them of the doorstep costs.
BTW, there is no problem (except additional cost) for couriers within Canada. This is a border problem only.
