How do I set my own postage rates?

[wineasap]

I want to set my own postage rates for Australia-wide delivery.

But eBay's Australia Post Postage Calculator is not accurate. We have an Australia Post account, and get cheaper rates than across-the-counter pricing. In some cases, eBay's Australia Post Postage Calculator prices are twice what we would actually charge.

None of the 3 postage options apply to this scenario:

- Calculated Postage - (is often wrong)
- Flat Rate (we don't want to offer a flat rate)

- Local pickup only (we deliver Australi-wide

How can I set my own postage rates?

As an example, Item # 150765177877 ( http://www.ebay.com.au/itm/McLaren-Vale-Reserve-Shiraz-Cleanskin-Wine-1-dozen-/150765177877 )
shows Postage option as "Freight - Read the item description or contact the seller for details". And postage rates are listed, and will be included in the eBay invoice.

That's what I'd like to do. Any assistance well appreciated.