It also depends how far ahead you book, because I see Singapore Airlines to Bali in January (I think) for about S$270, which isn't the cheapest, but at least it is a full service carrier (which means service recovery is usually decent). You'll get a meal on the plane and have check in luggage included.
Of course timings might not suit you, but this might be an opportunity to get out of Changi Airport and into town.