OK, thanks, I am guessing you see that info only when you are processing an article through ebay.

Would signature and extra cover be per normal Aust Post charges?

Yes, they are normal prices.

Once the item is sold,  go to your SOLD listings, to the right side of the item you want to post,  there are options and it shoud  say Postage label, click on that.

You  then go through the process of getting a label, you can find out all the price info and options. Before paying you can back out of it if you decide not to send by that service.