Read http://www.ccra-adrc.gc.ca/customs/menu-e.html, it lists everything you'd like to know about Canadian customs.

You'll probably gone for less than 24hours, meaning you're exempt from taxes and duties for anything under 50$. If you stay over 48hours, it then becomes 200$... 7 days or more, 700$!

I'm sure if you read enough you'll see something about hazardous goods.