On the "new tax" thing:
If something wasn't taxed, and is now taxed, whether something else already had that tax applied or not is irrelevant, it's a new tax on the good/services you're acquiring.
But anyway, all this will do for me is lift the burden of managing the $400 limit. If I pay GST so be it, I'll still be paying less than buying locally in a lot of cases (unfortunately).