To find out what stock the mint has you have to be registered to buy online at. http://www.perthmintbullion.com/au/View-All-Bullion.aspx
When you have registered to buy online you just login pick a silver product say you want to buy 100 1oz coins you enter say 1000 1oz coins and try to add them to your cart. If they have less than 1000 it will say sorry we only have 475 coins remaining please pick a smaller amount.
Then all you have to do is go through all there silver products to find out their total stock which has not been very much lately.
To register you have to give them all your ID details in the post it takes some time.I registered online about 6 months ago and found it alot easer to do trades with them than over the phone because you dont get put on hold.
