GST / PST and even brokerage fee (eg; UPS) for sure.
There's no way to avoid duty unless you want to smuggle something in; but I seem to recall that the amount of the duty will depend on the country of origin of the part.
Car parts made in the U.S. shouldn't be subject to any duty at all under NAFTA; however, parts made in Taiwan which I beleive no longer enjoys 'Most Favoured Nation' status, might have a duty of 6 or 10% (stab in the dark guess).
Check out the CRA website and see if they've got anything on it.
Canada Revenue Agency (they collect duty)
Edit: Duty is in addition to GST / PST brokerage etc. - you just don't see it that often any more, because we import so much that's made in the U.S. which is duty free.
