If you want to get it tested properly, I can highly recommend Parsons Brinckerhoff in Brisbane who do a postal check and certificate of analysis.
I spent quite a bit of time looking for a testing service that was a reasonable price.
Speak to Leah Raymont (contact details below), I found her very helpful.
In June this year, the price was $38.50 (inc. GST) per sample with a turnaround time of 2-3 days. The urgent test price is $50.00 (inc. GST) per sample with a turnaround time of 1 day.
Parsons Brinckerhoff
Level 4, Northbank Plaza
69 Ann Street
GPO Box 2907
Brisbane QLD 4001
AUSTRALIA