I was looking for a replacement for a relative's dying handset and saw these in the local Aus Post shop. All are prepaid and come with (or without) varying amounts of credit, and will be locked to their respective networks. Delivery is free if you can't make it to a physical shop, but it looks like the 6S is sold out online so you will need to check your local store for stock. There are several other models on sale, these look to be the best value IMO.
Optus X Lite $29 (was $49) - no credit with Optus prepaid kit
[Oppo AX5 $199)[https://auspost.com.au/shop/product/telstra-oppo-ax5-32270] (was $279) - with $10 Telstra prepaid kit
Apple iPhone 6S 32Gb Space Grey $379 (was $429) - with $30 Telstra prepaid kit
Has anyone got an Oppo AX5? If so, is it any good? The relative I'm looking on behalf of has an ancient HTC One that she's resolutely hung onto for as long as possible, but she's started to grudgingly admit it may be time to (finally) give it up, only because the battery dies after 20 minutes and she had phone calls cut off mid-conversation. I've heard good things about Oppo, I've just never had experience with them.