WW1 Australian Flying Corps Shoulder Title - Information Needed

[JakobVonBismarck]

Hey everyone.
Recently I purchased an Australian Flying Corps shoulder title from a trustworthy collector, along with a numerous amount of other WW1 and WW2 items.

I was wondering if anybody could tell me any information about this shoulder title, such as when they first originated and were handed out, also possibly whether it is original or not.
What would be the rarity for such an uncommon shoulder title, and how much do these shoulder titles go for on the market, as I could not find a single one online except for in the Australian War Memorial.

Attached below are some photos of the shoulder title, it looks to be in quite nice condition however it is missing one lug on the back of the badge. Would anyone recommend getting another lug and attaching it? or should it just be left as it is.

Any comments, feedback or information will be greatly appreciated.
Thanks
Jacob