I've done this and the math already. We had 3 of us on a shared family plan on contract with Sprint at around $200/month. We broke contract and ate some large

I've done this and the math already. We had 3 of us on a shared family plan on contract with Sprint at around $200/month. We broke contract and ate some large fees and sold our Sprint phones. We bought 3 nexus4 phones and switched to T-mobile that came around $100/month. Even after paying for breaking our contract with Sprint it was cheaper than to wait the contract out. As a bonus, we all got unlocked phones with Wifi tethering (free) and better data service. Keep in mind though, T-mobile signal might suck for your location.