Such a banknote does not exist.
The Australian One Hundred Dollar note was first issued in 1984.
The first Australian Two Hundred Dollar coins were issued in 1980.
All earlier Australian decimal banknotes remain legal tender in Australia even though they are no longer in circulation. You may have problems getting a shopkeeper of tradesman to accept an old banknote though. The Reserve Bank of Australia advises that old Australian banknotes can be presented at the Reserve Bank of Australia and most banks and exchanged for an equivalent value current Australian banknote.
between 10 and 30 dollars
The noun 'dollar' is a concrete noun as a word for a coin or banknote. The noun 'dollar' is an abstract noun as a word for an amount or value.
The first Australian Dollar coin was issued in 1984.
It's a novelty item and not a genuine US bill, so it has no value to banknote collectors.
There were no 1968 Australian Five Dollar notes printed.
There were no Australian Fifty Dollar notes printed in 1984.
Twenty Australian dollars
The Australian Dollar was going for about $0.73 USD in late 1994. The Australian Dollar is currently going for about $0.93 USD as of 3-Dec-2009.
In spite of them having been out of circulation for nearly 30 years, they are still considered to be legal tender and are worth one dollar. Most Australian banks will exchange one or two dollar notes for an equal value in current currency. Any collector value associated with a banknote would depend on the condition of the note, the serial number and the names of the two signatories.
The first Australian Two Dollar coin was issued in 1988.