just got my ASM skimmer g6 from the states and it was used, and didnt pay a cent in duties or GST. he declared it a gift and had a value of 50 bux. "Gifts from friends and relatives, valued at $60CDN or less, are duty and tax exempt. Goods imported into Canada, valued at $20CDN or more, are subject to all duties and taxes." you can read more about it on:
http://www.canadapost.ca/tools/pg/manual/b06-e.asp
but be aware that your goods can be held at the border if they feel that the declaration of the item is way off!