Aside from (usually more expensive) courier options, the only other alternative I know of is Skippy Post, but that will have some serious drawbacks / considerations, particularly in regards to eBay's late shipment defect system.
They will generally be cheaper, especially if you can ship out more than one OS item at a time, but the drawback is that individual packages won't show any tracking results until they are lodged with Skippy Post (you have to send all of your shipments to them first at a cost of $11, which is on top of the postage charges, they then on-ship via Singapore Post).
The transit time is also quoted as 20-30 days on average, which is usually a little beyond most customer's expectations, and would definitely be beyond eBay's ETA, so even if you didn't upload the tracking, I'm guessing most customers would start enquiring (or opening requests) before then, and would also have to answer 'no' to the on-time delivery question.
Which means your handling time would at least need to account for the initial transit time etc from you to Skippy Post, if nothing else, so you have a chance of getting a lodgement scan within your handling time. If I was going to use them for eBay sales, I'd probably set handling time at a week, which would also in turn affect the ETAs for Australian buyers.
Realistically, if your items are desirable (i.e. not readily available worldwide), I'd probably pick the best postage option that would minimise potential problems, and then let buyers decide if they're prepared to pay for it. Off-eBay, I'd be prepared to offer a wider range of choices to buyers (eg cheap but slow, fast but expensive, etc), but that sort of thing can shoot you in the foot here, unfortunately.
