You can order the Cowdroy P26 5mm track in 1220mm length from Bunnings. they don't stock it on the shelves but you can put in a special order. It is $18.60 per set. The 1800mm length is a bit wasteful if you are doing a 4ft enclosure.
Porks, are you doing a sliding track? Spacepac have the edge frame to make a swinging glass door, but I don't know if they have sliding glass track. It would have to be a ball bearing system if it is aluminium and $6 p/m would be very cheap! If you have a link we would all like to see it!!