You could consider setting up a package receiving account in a US border town. Many places that have post office boxes offer this. You pay a yearly fee of $10-20 and a small per week package fee for any orders you get (usually around $5 per order). That way you can get a 3 month supply shipped there in the week before you go from online stores which have prices no bricks and mortar establishment can compete with.
I don't know how far you live from the border, but if you use a decent amount of supps, it could be worth your while. Get together with a friend and it definitely should be so.
The reason I say 3 months, is you are allowed to bring 12 weeks personal supply and only pay the HST. Beyond that you are subject to commercial import regulations and possibly higher duties. If you get any guff from border agents for a 12 week personal supply or they try to charge a higher duty than HST, polite insistence to reclassify usually will work quite quickly. There are a lot of things you can buy in the States that are not allowed in Canada, like yohimbine, carnitine, DMAE, amongst others, so check the Health Canada website prior to ordering. You might get away with these things, but the risk remains.