not sure about a place here in OZ but you might want to try their US factory in the Gorge. There are a couple of shops there that sell Chinook and Dakine stuff online.
I've got a Slalom arm (152-214) that you can have.
This was a replacement for one that snapped, unfortunately 2 weeks after installing it the other arm snapped as well.
Chinook wrote to me and said that they had had a bad batch of aluminium, and gave me a new one under warranty. I would talk to the place where you bought the boom from.
Nebbs I'd love to take you up on your generous offer but I'm pretty sure the Slalom and Giant Slalom arms would be different lenghts.
I tried chinooksailing.com before posting here, but they only seem to offer back ends as replacement parts not boom-arms.
I'll get in touch with the shop where I purchased it to see if they can help.
By the way, I should make note that the damage is not a reflection of the build quality. A 90kg bloke hitting a sandbar at pace tends to break stuff no matter how strong it might be.
