To clarify in advance, I'm a B-scaler, so I've been on the expat housing scheme since joining as an SO.
Let me assure you that even with the full expat package, raising children in HK is NOT cheap, and it has become more expensive every year - application fees and debentures have gone up a lot over the years since my kids started school, and the government has now started winding back the subvention for ESF. And let's not even start with the waiting lists.
Want to get your child into an international school? As soon as you have a birth certificate, you need to apply, and that means forking out for a big application fee (NON REFUNDABLE). Maybe someone who's recently been through this can elaborate on exact amounts. As the school enrolment criteria is year of birth, then good luck if your kid happens to be born in December.
Then, if you're lucky enough to get a place, they start at 3 or 4 years old (depending upon the school and it system) and you're paying big $. Once again someone more current can elaborate, but a non-pilot friend of mine has his 5 y.o. daughter in grade 1, and I think he's paying in the order of HK$8,000 per month. For those that work in US$, that's a touch over US$1000/month.
Cathay pay some, but not all of the monthly fees, but don't pay for any debenture if needed, or application fee, or extra curricular activities like excursions, etc etc etc
In some cases, the application fee is in the order of a month's tuition fee, although some schools offset part of it against the first month of tuition.
I'll let you absorb that, before posting about the cost of after-school activities.
So, to summarise, raising kids in HK is expensive, but the big crunch is being able to afford a place to live with kids where the wife won't get cabin fever from living in a shoe-box.