Lion Air flies CGK-PNK 4 times a day for ridiculously low prices.
http://www.lionair.co.id/
Their web site booking is pretty flaky and has some serious quirks but I have successfully made it work before from the US with a US credit card.
I have successfully booked Mandala and Batavia paper tickets before from the US with
http://www.travelindo.com. But just e-mail them since the forms on their web site don't always work, and although they have been honest and straightforward with me, the process of dealing with travelindo is not for the faint hearted