Just thought I'd circle back with a new thread on this, as the total solution is across different threads and not quite complete.

For those of us who are new to Aus Post Business and are now moving to this platform to get savings on postage, this might demystify things for you.

If you haven't already. Apply for your Us Post Business account:

https://auspost.com.au/mypost-business

Go to settings, then integrations, then add your eBay account in there. 

Click the import button to import orders into MyPost from eBay.

Once registered with MyPost Business and starting to send parcels, it takes 8 weeks for them to work out what band you will be in and what savings that will attract. The bands and the costs savings are here as of March 2021:

https://auspost.com.au/content/dam/auspost_corp/media/documents/mypost-business-postage-rates-guide....