A good starting point for that would be eBay. Here's a link to help you in your search:
http://www.ebay.com/sch/i.html?_trksid=p2054897.m570.l1311.R1.TR1.TRC0.A0.H0.Xzte+savvy+battery&_nkw=zte+savvy+battery&_sacat=15032&_from=R40