Contact the seller and explain your problem.
Ask him for a Mutual Cancellation.
If he sends it, agree immediately. This will release both of you from the transaction.
Leave positive feedback. "Thank you for helping me with this." would be appropriate.
If he does not want to do the Mutual Cancellation, he can open an Unpaid Item Dispute. You don't want this, because either you pay (as you agreed when you bid) or you get a Strike on your account. Most eBay sellers have an automatic Block against bidders with Strikes.
In future, BEFORE BIDDING, check for the shipping cost to Canada. Also on low priced items, look for the words :
Customs services and international tracking provided
This says that the seller is using the Global Shipping Program which charges you duty and tax along with the price and the shipping charges. If your item is under $50, this will make it very expensive. (Over $50, you may be better with the GSP than with USPS/Canada Post shipping.)
