We've just had a run of breaking phones (2 weeks ago my Nokia Lumia 530 dies a death after I rolled on it working on the car, last week did the screen on my Nexus 7 tablet and on Thursday the wife broke her 3 year old HTC windows phone)
My phone cost me $150 2 years ago, and the replacement cost 180ish. Wife's phone was on clearance, and was about the $300 mark as well. As she looks after phones better than I do, she got a $300Lumia again. So if we averaged that out we pay about an extra $6-7 per month on top of the $40 Boost top up for the life of the phone. Looked at the price of a phone on a Telstra plan and just laughed... No where near as much data (11GB over 4 weeks for Boost, some of the Telstra plans were $80 for a phone and only 2GB of data per month)
I got burnt by a mobile phone contract in the UK, so I've decided after that to stick to pay as you go and bring your own device options. More flexibility for when you move and find no coverage....