I've used Bongo a few times - they ship DHL and don't charge crazy brokerage fees - after several large shipments i've only ever paid GST and $7 for the brokerage. You can calculate their shipping rates here:
Another alternative is to use a shipping outlet near the border such as http://www.montanashipping.com
- they give you the option to hold the package for pickup or forward via UPS/Fedex.
It's too bad there's no good Canadian sites to get auto parts. I've shipped ~$1600 USD in parts this year - including fees for the extra shipping, GST and brokerage fees, the same parts from a local dealer or Canadian website still would've cost me ~35-45% more. It's insane.