Three sites that might be useful for you
This site provides prices in US and AUD per gram etc
http://www.goldprice.com.au/
This sites buys / sells bullion and posts daily buy / sell
http://www.ainsliebullion.com.au/easyweb3/IDf9b48dc8771011/MIval=ew_view&WEBID=78594&ep_code=e004p01_stdEshop&page_code=buying_selling
This site tracks ebay
http://www.24hgold.com/english/buy_sell_silver_coins.aspx?co_id=15