Where to get cheapest iPhone 5s or 6 in New Zealand?

I currently have an iPad mini 2, my sister wants to buy it for around $350 and I could make some more money but I don't have much and I just need an iPhone because it's a lot more convenient and it can send texts obviously so does anyone know where i can buy a cheap iPhone? I don't mind if its second hand as long as it's at least 5 and works well.

You can get new iPhone 5 and iPhone 5C for $330-340 and iPhone 5S for $450 or so. So you can sell your iPad Mini 2 and get the iPhone in your budget and you can add little more to get better models. If you need iPhone without contract or unlocked at reasonable price, mail me for more info.