I’ve purchased a Fox Air Shocker from Partshark in November 2018. It was AUD$800 landed. I didn’t pay GST. Just this week, I’ve received some stuff from Spain costing AUD$400. Again, delivered to my door (no GST). I am aware that all imports, even those costing below $1,000 are meant to attract GST now, but from my experience that seems to be limited to sellers who are participating in the ATO GST program.
Yeah there's a few things that come into it, and the freight company and how you pay plays a big part.
First up you should have paid tax on both of those items, it's great that you didn't, but if everything was done correctly then you would have paid. I buy work related products from a range of companies from numerous countries and I never avoid the government hand out. Mostly I'll pay at the time of purchase, sometimes I'll have to pay to release it once it's in Australia, and on one occasion I had to pay to the transport company after a knock on my door about two months after the item was delivered. I think it was Toll, but don't hold me to that.
I've noticed that even my Website provider that, while presenting itself as an Australian company, never charged GST, which it would normally be required to as an Australian company. They are actually a Dubai company which is why they didn't charge GST or use proper invoicing. About a year ago that all changed, this Dubai company, operating within Australia, now has to follow all the typical GST rules. They are cracking down on everything, and fairly hard.
In the case of an Ebay transaction, it's Paypal who do the GST compliance. Below is what my screen looks like if I were to go ahead with the purchase.