[https://us-store.acer.com/4-cell-li-ion-2500mah-battery-1|If you are in USA, then you can order one from Acer's Web store.]
'''Part# AK.004BT.098'''
"4-Cell Li-Ion 2500mAh Battery"
$39.99
Their marketing/ordering/stock part number AK.004BT.098 corresponds to battery model AL12B32, for Acer Chromebook C710.