And if you don't buy an iphone or the NEWEST phone it's for sure saving a lot. For example You can buy an HTC one for well under $400 right now. And a Nexus 5.
The windows phones are even cheaper ( thought not as great. )
It can potentially save you a lot of money.
With the family plan these phones are 50-100$- which saves me $300 right there.
And IMO they don't last more then two years,
So your not saving THAT much,
And if you need more the one gb Internet- not sure saving at all...