The Ngineering product numbers for the tubing are:
Ngineering 0.042 inch stainless steel tubing - N2042-2 (2 pack) or N2042-4 (4 pack)
The only source for this tubing that I have found in Australia is the Model Railroad Craftsman at Blacktown NSW. The tubing is not listed on the web site shop so must be ordered over the phone or of course by purchasing at the shop.
Alternatively Ngineering has a web site from which the tubing may be ordered:
Instructions for cutting the tubing are available on the Ngineering web site here:
I investigated the Ngineering shipping cost to Australia and it was US$10.00
If you wish to light the signal lamp then the hole in the 0.042 inch tubing is large enough to easily fit the wire on a 0603 SMD Warm White LED and might possibly also fit a second set of wires for a signal with two signal arms on the one post.