The maximum wholesale price is around ~$19/kWh (inc. GST) throughout most of Australia, and $21/kWh in SA (inc. GST). Prices this high are very rare, with prices ranging from $3/kWh to these peaks historically occurring fewer than nine hours each year.
These maximum prices aren't set by Amber. Instead, they're based on the maximum price that generators can be paid for their power - a price which is capped by the energy market operator (AEMO).
This is the true price we must pay the generators and networks for your usage during price spikes.
If we artificially capped the wholesale price we would need to recoup the difference elsewhere, by charging you more per kWh year-round to cover the cost of your usage during price spikes.
This is exactly what the big energy retailers do. They don't care how much power you use during spikes, because they charge you more year-round to cover the cost (and then some!). Many of the big energy retailers also own and operate the expensive and dirty power plants that make most of their money during price spikes.
Instead of a price cap, we add a small <1c/kWh hedge to the wholesale price year-round which we pass back to customers in the form of our price guarantee: over the course of a year, you'll never pay more than the government reference price for power (on average), or we'll refund the difference.