How can I find out if there are import or duty charges when I purchase something out of canada

[reallynicestamps]

http://www.cbsa-asfc.gc.ca/travel-voyage/pdt-pdt-eng.html

Start there.

BTW, even if duty is not applicable to your item, you will have sales taxes (GST/PST/HST). Sales tax does apply to used goods.

In addition, the shipper will probably charge a service fee for wrangling the parcel across the border.

Import charges start at $20 CDN (about $18USD)