Coast airbrush and Bear Air both carry spares in the states, but if you are in Aus, Rainbow 10 is just as easy.
Yeah, I needed a spare ( read as : replacement )needle pretty quickly, it's about US$11, but the tip was $42 !!
Be really careful and do not bump into anything when you've got the crown off.. actually take the needle out FIRST.
I found that the old needle, reversed, made a great trigger holder while cleaning. Just run in in far enough to engage the trigger parts and then clean away w/o worrying about losing the trigger.
A bit of equal sized brass rod works just as well,
Have fun, it's a great gun.
Mike