ABS brake specialists are a brake repair chain you can get steel tube through easily enough, although Wombat had trouble with them up in Qld. Other than that, any brake repair joint should be able to get the tube in.
Some classic car specialists are able to get in the silver zinc plated lines, although usually these days you will find it to be the green plated stuff which satisfies the euro pollution standards (cadmium falling out of favor as the next most prevalent heavy metal found in road run-off).
The double flare tools are easily available on ebay, make sure they will perform the double flares however as there is plenty of single flare kits out there as well and they're not that different to look at (double flair kits have a number of small dollies included).
The cheap kits on eBay will perform the job, although the clamping bar provided needs to be squeezed in a vice to grab the pipe with enough force...also it pays to use the next size down dolly when you perform the flare. Simple to understand instructions are on the back of the packet.
http://cgi.ebay.com.au/FLARING-TOOL-KIT ... 2ea7fc2f38
I did a complete set of new lines using this set from front to rear (including hydro lines) and did not have one leak from any of the joins.