House prices are crazy. A couple of houses are for sale in my street. I could easily buy a château in France for that price and the quality of the house would be so much better.
Renting is very high. And I mean really high.
Sadly on domain or real estate (the other website for renting) , you can't see how terrible the houses in the lower prices are. If you put a limit at $1000 with 4 bedrooms and have only a very few options, they are probably very bad. And I mean very bad.
If you are coming here because you are under financial stress in London, reconsider, because Sydney is way more expensive.
Fruit and vegetables are often good quality, but very expensive. When I did my big first shopping at the supermarket, I was shocked when it came to paying.
Even stupid things like a Pantene shampoo cost triple, so I buy a stock when they are on special.
Cars, buying and running a car is very expensive and depending where you live, you will need two. Because the kids will have activities, soccer games, and you can't use public transport for those. Even the beaches. There is a strange thing (strange for a continental European, maybe it is a thing in UK), and it is the double insurance you must purchase for the car, one for you, one for the third party called green slip, even if you have the platinum insurance.
Going anywhere will cost a fortune, this is why so many do camping. Going to Europe is very costly in terms of money and time.
Entertainment such as theatre or opera is sooooooo expensive, books as well (book depository has different prices for OZ), Amazon doesn't;t deliver here, you can only use Amazon Australia (and very rarely Amazon USA) and the choice is rubbish.
Health is very expensive once you need something more than your basic GP. Specialist will charge you 300-600 and medicare will cover 70. Only if you are seen - in very rare cases - in hospital will the visit be free. Private health insurance doesn't cover for specialists or imaging. Dentists are crazy expensive but will be covered by private insurance, but the cover needs to be high to really cover for all.
Coming to Sydney on a budget is doable but why bother then? If you come to Sydney it is for the way of life. If you have to go deep in the West, away from the beaches and bush, it is only a worse version of London with blue skies.
Look at Maroubra for a good balance of price/lifestyle.