Originally Posted by
unagi1
There are two money changers right at baggage claim, Amex and I forget who the other one is, maybe OCBC. I don't use them to change money, but I know that either one sells SIM cards and top up cards. As stated here also, if you prefer to wait until you're in town, you can also get them most anywhere.
I was in Terminal 1 (arrived on Jetstar) in June. Right next to the customer service counter after you exit the sterile area, there is an AMEX counter. I bought my SingTel SIM card there. I, too, was hoping to get a SIM card in advance but couldn't find any, but this AMEX counter was pretty quick and easy. The taxi stand is about 30 seconds away, so you are on your way once it is done.