Don't forget the domestic airport taxes. DPS is the most expensive at 75k IDR. Not sure if you're charged on a connecting flight, but I'd guess so. If you transit CGK, hopefully you stay in Terminal 3 which should be easy.

I've heard that they will start to include airport taxes in tickets next year, but don't have any real details, yet.

I've found skyscanner.com (or the Indonesian version) to be quite a nice way of finding fares.