If you are in Canada and buying from Amazon.ca, then you are buying from a Canadian company "in Canada". Just because the product originated in the UK doesn't mean they should be able to charge you duty on it. That would be like going to your local CD store, picking a CD off the shelf, and being told at the counter "since this band is from the UK, you have to pay duty on top of the sticker price and HST."
If you are buying from Amazon.co.uk or they are explicit that you are buying something in another country, not paying Canadian taxes, and it is being shipped over borders, then you could get dinged. Typically, you would basically be paying Canadian sales tax on whatever the value of the product is... so less than $2 on your $12 CD. I wouldn't be worried about it for such a small ticket item either way.