I just click on the "awaiting postage" tab in the seller hub.  It takes you to "Manage items awaiting Postage" and I can then print a list of all the items awaitng postage and print all the invoices.  I just tick the items off the list as I pack them. 

I then go to the Australia Post "My post Business" website and select "import eBay orders" and all the postage details are downladed into postage labels.  Once I print the postage labels the tracking numbers are attached to all the eBay purchases on eBay and they are marked as posted automatically. 

There are five tier levels on the website with up to 40% discount available on some parcels and small local parcel rates from $5.37.