We go by the standard postage costs as provided by Australia Post.
In some cases, smaller items can be sent as large letters instead of small parcels which significantly reduces the postage costs.
In these cases we will refund the difference to you once we have confirmed with the post office. Unfortunately this happens on a case-by-case basis, depending on the Australia Post employee we're served by which is why we initially charge the full cost upon checkout.
If you have any questions about postage, please feel free to email us at email@example.com.