You have to ship EXPEDITED to avoid brokerage fees.

Expedited means that the shipper fills out the form for Customs that states the correct code for the item in the package so the proper duty is applied (for example 5% GST, or nothing depending on the item).

Without the paperwork done ahead of time, someone at the border does this for you (a broker) and you get to pay a nice happy service fee for their trouble. Chances are they'll put the wrong customs code on the item anyway.

You may pay a little more for expedited shipping up front (because they're filling out paperwork for you), but the item will spend a lot less time at the border and you avoid brokerage surprises.