Shamatti
The Perth mint ceased making the 20oz Perth Mint bars years ago and... for some time, there were quite a few people who wanted the 20oz bars and of course... they had a premium.
Last year (2013) Perth had old stock that they decided to release; they were available from their Perth Mint Bullion Web-site.
For awhile, during the new release, dealers like Perth Bullion company, formerly (Bullion Bourse) who resides in WA could not aquire or had no desire to aquire stock but at the request of his customers they now have them for a limited time period.
When the 20oz bars are no longer available / dried-up from dealers...that's it...there's no more unless The Perth Mint decide to pour new 20oz bars which they have no intention of doing.
They are a very good bar to accumulate.
Perhaps not of a premium today but certainly a premium in the years to come.
H