Buy and Carry bullion from USA to AUS

I am travelling to USA next week. in Palo Alto area.

I am planning to buy some silver bullion. Just wondering how much I can carry with myself not t pay any GST when entering into Australia?
I heard that if it is bullion an the total value is less than $1000 AUD, then it is fine. Is it?
How they value the coins? Do they ask for the invoice?
What will happen if I carry more than $1000AUD value of bullion?

 

i always carry 10000 20000$ never be charged any tax
i never declare real value its too risk

i always didnt write any coins on the form

at least within 10years never got pro

 

Just show them the face value

 

and get some junk silver as well.

That has a face value and is still legal tender so a couple of rolls won't really dent your allowance.

 

Thanks, everyone for the suggestion.