You can look up the codes here:
http://www.canadapost.ca/cpotools/apps/wtz/business/findHsCode?execution=e1s5
Declared value should be the selling price. The official US free limit is US$200, in actuality for items sent by mail from Canada it extremely rare for a package to be charged duty or require full customs processing if the value is below $2500. Shipments sent by private carrier (UPS / FedEx) always require a formal customs entry if the value is US$200 or more.

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.