Can't help you with the trade - you might try the Canadian Exchange forum - but it is interesting how few people realize that cacti species are native to Canada.

Here is a link that might be useful: Native Cacti in Canada

We have rolling cactus on our hills above town.Those little balls that just sit on the ground, waiting for you to step on them. Down near the border, by Osoyoos, it is true desert. Everything but the tarantulas.

I was reading a magazine (Canadian Geographic, I think) at the gym the other night. There was an article in it about tartantula species that occur in BC - some known for some time, others expanding their ranges. Not exactly the really hairy guys you see in the SW US desert, but good-sized ones, anyway.

There are many cacti species that can survive in Canada! I'm my zone 5 ish garden in fernie British Columbia I have about 30 species that survive outside! Have you looked into the cholla cactus? They are deffinetely worth looking into. Many types are hardy in our climate! Good luck with your cactus gardening