Hey,
Also from NZ. Been to Bali 5 times and will be over there in a few weeks Yay!! just call voda and set up roaming, ask them who the cheapest network is to use while over there, from memory i think its INDOSAT? You can text using your own plan and you do not need bali sim. texts are about 30 cents i think. Not worth stuffing around buying another sim. As soon as you land, switch ph on and wait to get all the network providers messages and then chose the one you want. Have never had a problem even texting 027.
Cheers