So, kind of a crap shoot, right?

 

You are correct about Australia, under 1k causes less problems but recently it's 10% tax with online purchases. Stuff gets through all the time.
When I got my 351 kit with carbie, that become stressful as they make it too difficult to figure out so you have to pay someone to get it sorted with a limited time frame.
FYI Aussies, if you are buying multiple items worth more than 1k aud, buy separately!