Trevor, that may be correct, as far as it goes, however, what then transpires if the clearance costs are fixed at a high value, as someone else suggested. Add the GST cost to goods of $100 may only make $10 difference, not much in the grand scheme of things. But, lets say, that clearance costs are fixed at $80, for goods under a $1,000, then that $100 suddenly becomes $190 ($100+80+GST) and that would make a difference, and the government would collect more than it costs to collect it.
As I have previously said, that if that scenario were to occur, one will just bundle items to come in just under $1,000 (which includes freight). Then that $80 is spread over the $1,000 which will be a cost of $8 per $100 plus the GST. I think paying, say an extra $8 per $100, may just make me reassess that situation, or I will wait and bundle more items together to make it worth the extra cost of clearance and freight.
I also paid around $80 fixed cost to clear my FLT 110, and I would imagine it probably takes the same amount of time to clear an item worth $100, as it does to clear a package that cost $2,250, so it is reasonable to think a fixed cost for clearance would be a likely factor, in determining the outcome of the review. The really scary scenario would be if they found that the $80 clearance cost was actually too low.
So, I think, given what I usually save, I probably would buy it locally, as it just won't be worth the hassle, particularly adding the time and my fuel cost to go clear it.
But, I will add this, if service doesn't pick up as a result, then stuff the local suppliers, I will buy it from whomever gives me the best service, whether here or overseas. Hang the extra cost, just means I have to work an extra couple of hours. I will not reward a company that gives poor service by giving them my hard earned dollars. If they want my business then they'll have to earn it. And if we all did this, it would send a strong message to those companies, as of right now, they simply don't want to do anything and expect the government to fix the problem for them. It seems now when a company gets into trouble it goes screaming to the government. I don't have a problem with government supporting some industries, but there has to be a productivity trade off. The unions won't allow any changes, so the company often has no other option than to close. I have had that very thing happen to my job, more than once. But then, I just went and found another job, instead of moaning about it. Some of those jobs weren't at all pleasant, but it paid the bills.

You do what you "have" to do, not what you "prefer" to do, the real world just doesn't work like that for most people, just the lucky few.
By rewarding poor service we just propagate the problem down the line.