I would buy from the states if there was a specific bloodline, morph or species that was not available in Canada. Also, if the right deal came up, I would jump on it. But I have found that ALMOST everything that I want to work with is available here in Canada now or is in the works and will be available in the near future.
As far as selling goes, my stance is this, if someone steps up with the money but happens to be from the states and is willing to pay the extra money for the paperwork and etc, I would sell to them... Why not?
I think the market in Canada will always be behind the US though. With a smaller population, we have a smaller reptile "market". We also have our major cities much further apart from each other and a LOT of shipping is required... not sure if this makes any difference.
Anyway, those are MY thoughts...