Everyone in my office paid around 7.5-8.5k AUD for batteries around the 24k mark, so I know this to be the case. I could email you the invoice if you don't believe me xD

You can read up on the subsidy itself too - they basically set a cost per kwhr target based on the few bespoke batteries on the market, before it was flooded with cheaper Chinese options. Because it was based on capacity rather than a percentage discount, this caused the effective discount to be much higher than intended at the outset.

We don't know the final numbers yet - but government has reforecast for 7 billion for the program's duration, which includes a much smaller subsidy continuing until 2030. I expect it will be close to about 5B spent so far.

The program is of course much more complex than can be fit in a HN comment, and it has evolved over time. The simplest answer is the government contributes $252/kWh. Approx. 4x the cost if the government funded a utility scale BESS - noting the installed cost of a home battery is 400-1200$/kWh depending on brand/options etc.