I've bought them from Amazon, and from other online retailers with no problems. Best to speak with someone in person, before you commit, and get them to put eyeballs on them to see the expiry date. Calculate out your rate of consumption (may as well throw in a few spoiled ones!) and see if you'll finish them before they're gone. My last set were 48 strips which expired in three batches over the course of one year. That worked for me, and if I recall correctly I paid under $4 per.
I haven't the faintest idea about customs because I was in the US for quite a while, and receiving them there. Now I'm back in Canada and I'll be curious to know what you find out about duties/brokerage. If its going to be an issue, I'll just send them to a friend in the US and pick them up when I visit.