Australian coins are interesting and a fair number of commemorative coins disappear from circulation quite quickly. The color 2 dollar coins in particular are just hard to find in general. The Royal Australian Mint do release roll coins for special occasion, often at a high premium. Most coins often come in bags.
What really hurts is that the postage fees is absurdly expensive and the weight of Aussie coins in general are just too heavy, making postage very unfriendly. Honestly, imagine if you wanted a date run of all 50 cents coins plus commemorative but not including varieties...
My partial coin collection
http://www.omnicoin.com/collection/gxseriesMy numismatics articles and collection:
http://www.gxseries.com/numis/numis_index.htmRegularly updated at least once a month.