Is it? USD 450 is currently AUD ~670 according to DuckDuckGo. 10% sales tax on top of that leaves you at AUD 737. An AUD 13 premium in that price bracket is ... negligible. At worst. I would call it a rounding error.
The edit button is useful
Beyond that, OC isn't likely to get better - the voltage needed to get the Ryzen architecture (at least on TSMC's low-power processes) to go faster is too high to run safely 24/7. Minor gains can happen, but generally things will stay put. Still, there is value to forcing a high all-core clock for a render rig or something similar, in which case manual tuning and beefy VRMs are useful. But you likely don't need the C8I, no. And for everyday, average use, the best thing to do with Ryzen 3000 chips seem to be leaving them stock and/or letting them have all the power and cooling you can give them.