If the screen size between those two models don't matter to you, and you care about the processor and battery life instead, the iPhone 13 mini should be a better option. The battery is the same between those two models, but the 13 mini has a better chip which should help with better performance and graphics. And considering its newer it should last longer and be supported for more iOS versions to come. In addition it has some new features, such as MagSafe charging.
I took a quick look at Australia's Certified Refurbished Shop, for some reason they don't sell iPhones at all. You are left seeing if nearby Apple Authorized Resellers have that model in stock, as Apple no longer sells that model.
Find Locations - Apple
But be careful as Katana-San states and don't purchase from any unauthorized resellers. Many people end up with a damaged, defective, Activation Locked, carrier locked, etc device. We see it here daily. Do yourself a favor and keep your hard earned money.