OP is not asking whether they have to pay tax or not, rather whether they may be on ATO audit list.

In short turnover as far as ATO is concerned is money coming in inclusive of post. Listings whether as post added or free post may make the difference as to whether you are on Ebays supplied list.

Ultimately if you are around the 10,000 mark you are unlikely to be audited on Ebay reasons alone. They know 10,000 raises not much profit. So if you have other income they will just want to see you have declared something. TBH I believe they reduced it to 10,000 mainly to "frighten" lots of small sellers to actually get in the habit of declaring.

If this frightens off a lot of potential little sellers from thinking it is all too easy, then all the better to reduce my competition.

I am sure most people would prefer not to on an audit list regardless of how up to date their records are.