Green’s Dictionary of Slang

(Aus.) a $100.00 note, thus half-a-Bradman, a $50.00 note.

2013

T. Peacock More You Bet 67: The ‘$50 note’ is sometimes referred to as [...] ‘half-a-Bradman’ (after the great century-making batsman); while ‘$100’ is a ‘spot’ (as was 100 pound), or a ‘Bradman’ or a ‘hungee’, as it is sometimes referred to, particularly by younger people.