The buyer doesn't pay postage to ebay. That's not how it works. The buyer pays the seller when they pay for the item. I suspect the issue is as others have mentioned, your funds are on hold for 30 days. Yes, you will get paid, but you will need to pay the postage upfront. Once your funds clear, you'll be reimbursed the postage you paid. 

If you're going to become a regular seller, plenty here would recommend not using ebay labels. As you have been using them, I assume you have a printer. Instead, go to the Australia Post site and create a My Post Business account. It's very easy to set up and best of all, it's free! As in no charges to use it, you still obviously need to pay for the postage. 

Most of the time you can link your ebay account, so most of the buyer details are populated already. If it doesn't happen, it doesn't take long to add the buyer details into the form. If you start to sell a lot of items, you will actually get postage discounts, which can really start to add up if you're busy. It's very well worth it. 

As an aside, please don't play the disability card. There are quite a few disabled people in these forums, who are broke and also old. We come together as a community to help each other out, whether it be buying or selling. I'm sorry you have to sell off your possessions. I do hope things improve for you soon. There are plenty of us doing it tough. Hopefully we'll see some sunshine soon!

I noticed most of your sold items, you've accepted best offer. I hope they weren't really lowball offers. Don't ever accept low offers. For the items you've sold, I'd accept a few dollars off. Personally, I'd be removing best offer, because they are items that people would want and probably be happy to pay the asking price.