In Reply to: follow up posted by 96822ivan on Saturday, 16. February 2013 at 12:22 Bali Time:
The sim costs 5,000rp less than 50 cents US. They add credit, usually 50,000 or 100,000 $4.50 US or about $9.25 US respectively. Now the problem. Some charge to sort your phone out for you. eg putting in the sim, adding credit. could be as much as $5 US to set up but some do it for free. A lot will add credit 50,000rp credit they charge 50 cents Whoppie.
I Go regularly to Bali, Have 3 sims and take them back. A few phone calls, reasonable internet costs about 100,000 per 7 days, but lots of places have freen WiFi so you can cut down on Data.
BIG PROBLEM FOR YOU TO WORK OUT NOW ==== IS YOUR PHONE LOCKED
You have not named where you are staying so hard to recommend anywhere to buy a sim.