or you can use a third party company that will provide you with a PO box in the states and you can go pick it up there. i use Kinek.com. it costs me $5 to have items shipped to a UPS store 3 minutes from the queenston-lewiston bridge. you're able to get better shipping rates, quicker delivery (next day most times, no customs holding packages for undetermined amounts of time) and if you catch the border patrol on a good day (or are willing to risk it and lie that you don't have anything to declare) you'll avoid any duty.
I use cbi-usa.
ALWAYS DECLARE SOMETHING. It doesn't have to be your lenses, but it's extremely risky to declare nothing and cross.
Camera stuff is duty free. Try to get it shipped USPS. Fedex and ups can hit you with brokerage fees.
I would pay for insurance on $600 lens