If the seller is in US, then don't buy it.
Not only need to pay Canadian TAX, but also you need to pay something kind of brokage fee to UPS(very high...)
You are not suppose to pay US local tax (8.35%) if you are in Canada. Sipping though USPS doesn't have brokerage fee. Both UPS and FedEx will charge brokerage fee on top of pst and gst payable to CBSA.