I've used CanadaDrugs with good result. I have seen other mention Northwest Pharmacy? I know there are a lot of cheaper ones but you have to look for reputable ones.
There was a wonderful post once where someone broke down the pharmacies up n Canada, I will try to dig it up for you.
This one provides a ton of good information:
www.healingwell.com/community/default.aspx?f=38&m=2169778