" ... I have a Customs Broker for imports from the US, so when I use th ..."
... when I use the Broker it's USPS Domestic to the broker's US warehouse (typically 5 days), they carry it across the border and re-send it to me Purolaotor Air (1 day, cost is up to $C 20 [$US 15] depending on size / weight. Since a USPS Flat Rate Box is $US 50 and three weeks, and many packages are larger / more expensive than that, it's much cheaper as well as faster that way, even including brokerage fees.
... when I use the Broker it's USPS Domestic to the broker's US warehouse (typically 5 days), they carry it across the border and re-send it to me Purolaotor Air (1 day, cost is up to $C 20 [$US 15] depending on size / weight. Since a USPS Flat Rate Box is $US 50 and three weeks, and many packages are larger / more expensive than that, it's much cheaper as well as faster that way, even including brokerage fees.