If I were you and your interest was Australian Militaria then I would look at using Dealers like I.S.Wrights or Nobles Numismatics. With regards to the Cap it appears to be 2ww, the insignia should be brass, possibly made by Stokes.
thanks mate going to make it a project got several better looking hat badges ( i wont rubbish this hat badge)
similar Caps were going for $300 way out of my price ranges. This Cap was bought from I.S.Wrights account on ebay.
thanks for your input