Private/International schooling in HK is no more expensive than in Australia unless you take the Catholic school route in Australia.
We're still deciding between the AIS and ESF.
My child attends the kinder and I can't speak highly enough of it.
That is not to say there no glitches in the system. The class size is larger in ESF. Most of the kids in our neighbourhood attend an ESF school and the parents have helped us in our decision - kid's behaviour too. We are leaning towards ESF as the kids seem happier and more polite. Parents were more down to earth. It fits our needs.
I would say, if you're from Sydney, think of going to SCEGS or Sydney Grammar or Melbourne - Melb Ladies College, Korowa or Wesley... I don't think it's any cheaper. I know that our child would have attended a private school in Australia so we aren't whinging about the costs and opportunities of private/international education here. All private school kids in Australia require a laptop now unless you're in Scotch College unless they've changed their policy.
Unless, you're a parent who's set even in your home country to send your kid to a local primary school, it would seem HEAPS MORE expensive. And, would have a lot of issues with how expensive education is in HK.
I am aware though that there is no PERFECT solution in HK. It just depends on the parents. The are good local school options. PM me and I'll send you a few recommendations (not the ridiculously hard to get in schools)!