OK Gary, here we go. Next to each item I've put whether I can help you with this and the grade I have. If I cant help you I'll comment on how to get it.
Twenty Cent Pieces1971 - Yes, F
1979 - Yes, F
1983 - No, most of the mintage was melted, mint set only coin
1984 - as above
1985 - Yes, Gem worth about $15
1986 -
no mint set only coin
1987 -
no mint set only coin
1988 -
no mint set only coin
1989 -
no mint set only coin
1990 -
no mint set only coin
1991 -
no mint set only coin
1992 -
no mint set only coin
1993 -
no mint set only coin
1995 Platypus - Yes EF
2001 Bradman - Yes aUNC
2001 New South Wales - Yes aUNC
2001 Western Australia - No
2001 South Australia - Yes aUNC
2001 Tasmania - No
2004 (Large and Small head varieties. I have one, not sure which) - The small head has a pointed A in Australia and is quite scarce. I can offer up a large head in EF.
2005 Platypus - Yes EF
2005 60th Anniversary of WWII - Yes aUNC
2007 Lifesaver - this is NCLT, currently the cheapest way to get this coin is via a PNC (selling for around AUD$20) or via the 2007 mintset (US$23.50).
Fifty Cent Pieces
1966 - Yes aUNC
1981 Charles and Diana - Yes aUNC
1985 - Yes essentially a mint set only coin, worth about $15
1986 - No, mint set only
1987 - No, mint set only
1988 - Yes, UNC worth about $10
1989 - No, mint set only
1990 - No, mint set only
1992 - No, mint set only
1993 - No, Scarce circ coin
1994 - Yes, VF
2000 - Yes, VF (this is the millenium coin I assume)
2000 Royal Visit - Yes, EF
2002 Outback - Yes EF
2002 50th Anniversary of Ascension - No, unfortunately these were on a PNC only and that PNC goes for around $200
2003 50th Anniversary of Coronation - No, again on a PNC only but these go for around $25-30
2005 60th Anniversary of WWII - Yes, EF
2005 Coat of Arms - No
2006 Commonwealth Games X 16 - No, you'd have to buy these as a set, I think they go for $150-200 or so.
2006 Queens 80th Birthday - No, comes on a card for around $20-30
2006 Queens Royal Visit - No, again comes on a card for around $20-30
So there you have it. I'm not sure what you'd want to trade. I am mostly interested in world silver and so on, junk silver is fine too. Perhaps email me so we can work something out.
Mark