fine gold can be found anywhere.mostly from chips off large picks that people dig up.the best is to get nuggets around 0.5g to 1.5g .as these are at nice price. if you want to invest go for the larger ones,but check over to see if they have quartz, this will put the price down a little.(as gold is worth more than gold).
large pieces over 5 grams are hard to find,so price are likely to be 2 1/2 time more or about in price .gold spot(value of gold per oz) can go up and down all day. so check the daily gold spot before buying. note add 10 to 15% to the gold spot, for the right price of nugget.as some sellers will rise the value because of shape,colour and form.

hope this help ya out.if you need more answers just  pop into chat room when the live auctions are on.site manger and lots of the locals are on at that time of day/night

and  the answer to the question - i would buy nuggets are 0.5g to 2.5g
and yes Australia has some very fine gold nuggets. Victoria has golden yellow nuggets and western Australia has some nice reddish nuggets