I bought a 480GB SSD from OWC this past December. They shipped it via UPS and, much to my surprise, I paid NO brokerage fees. You will of course have to pay GST when it arrives unless OWC/MacMall charged that on your invoice.
I have yet to figure out, reliably, when brokerage fees are applied. After going to the UPS and FedEx web site I was only more confused. Because brokerage fees can be as high as 40% of the purchase value of the product I normally refuse to do business with any US company that won't ship via USPS (which has no brokerage fees).
I hope this helps, but I can't definitively say you won't be charged brokerage fees.