If you have an existing line and satisfied with your data amount, calls, and text. Just get the phone straight from the apple authorised dealers. They offer 0% interest instalment from 12 months up to 36 months via selected credit card. So essentially you are just paying the phone rather than signing for telco that you have to pay not only the line but the phone as well.

The saving part that is mentioned by them is usually you have to sign a plan, then get the phone at a discounted price (correct me if im wrong). But the total price in the end that comes out from your pocket will always be more than buying just the phone