The MotoX is an awesome phone. I’m using and loving it on Republic Wireless’ $25/month unlimited talk, messaging & 3GB plan. You can get unlimited talk & messaging with a $5 wifi only plan too or pay $40 on the unlimited 4G phone network. No contract required for any plan and the MotoX sells for $300 (or get a Defy for $100).
Here are some good tips on how to care for its battery and make sure you get the optimal length of time between charges.