All amazon.com shipments come via Canada Post i.e. mailed within Canada for the Canada part of the journey. Been like that since the beginning of amazon. The difference in the last year is the shipper between amazon (.com) and Canada port of entry. Now it's DHL, and now you have to pay "import fees". One of the secrets of the "old" amazon.com is there was no "import fee" (CP charges $5) or taxes...you can see the benefit right there. Now you have to do some careful consideration as to which amazon is cheaper overall.
One other thing I can suggest is to check the amazon.ca sellers *within Canada* for their prices on new CDs. Often cheaper than amazon.ca even with shipping charge. I have had great success with some of those sellers in the TO area, and in fact I look for them first for supplying me (before amazon.ca I mean) they have been so good. They bill through amazon so you use regular CC and no PP BS.
Shipping rates are fixed by amazon so no eBay ripoffs there. I usually get stuff the next day. I really wish some of the TO amazon affiliates had a store because they seem to have so much cool stuff, yet amazon doesn't allow you to check through their whole online "store" to see what else you may want the way eBay does.
More edit: just went to mailbox and got 2 amazon orders. Yeah, I am a CD/BD junkie...
Price comparison of one CD I just got, this is for the *identical* CD with same ASIN: