These are third party ones, but are really good!
I use them myselfs.
http://www.amazon.com/Battery-Anker-2200mAh-Replacement-Samsung/dp/B00A44JSFK/ref=sr_1_1?ie=UTF8&qid=1449850129&sr=8-1&keywords=i9300+anker
http://www.amazon.com/Battery-Anker-2200mAh-Samsung-Replacement/dp/B00GHDLR4C/ref=sr_1_2?ie=UTF8&qid=1449850129&sr=8-2&keywords=i9300+anker