Which issues would qualify as an "emergency stamp?" If they're worth some significant money in blocks of four I probably don't have any. My Australian stamps range from about 1974 to 1992.
Emergency issues are not common and always command a premium. For instance, 52 years ago the supply of 2/6d Robin stamps, issued on April 26, 1965 proved insufficient to last until February 14, 1966 when the Australian Pound, Shillings & Pence were converted to Dollars & Cents.
A reprint of the Robin was not practical due to the heavy use of the photogravure press for the forthcoming decimal issue. To fill the gap, a new printing of the 1952 & 1957 Aborigine was released.
As far as it is known, the stamps were distributed to post offices only in New South Wales, Queensland, Victoria & Tasmania. The emergency printing was in a distinctive light sepia-brown on the whiter paper which had been used for the August 1964 printing.
ACSC 265A) 1952. Aborigine. 2/6d. Perforation 14½ x 15. Sideways C of A watermark
ACSC 266A) 1957. Aboriginal. 2/6d. Perforation 14½ x 15. No watermark
ACSC 267A) 1965. Aboriginal. 2/6d. Perforation 14½ x 15. No watermark (Emergency issue) on whiter paper
ACSC 421) 1965. Scarlet Robin. 2/6d. Perforation 13½. No watermark. The depleted Robin issue
ACSC 458A) 1966. Scarlet Robin. 25 cents. Perforation 13½. No watermark, in darker shade. Replaced the emergency issue
My emergency issues (including later issues) are singular, but to have a block of 4 stashed away can bring in a few dollars on a rainy day.
They are not expensive but do have a monetary value. At the moment there is a great hype concerning the 2016 Adelaide emergency issues of unofficial 30 cent stamps printed at a post office.
When first discovered, they were being sold on eBay
for exorbitant amounts of money, one set of 6 was sold on eBay
To me it's a waste of money; major stamp dealers won't touch them, Stanley Gibbon's will not price them as the company views the stamps as labels, and the Australian Commonwealth Specialists' Catalogue will not be issued for another 3 years or so.
A catalogue that includes emergency issues will explain the purpose of the stamp; the information I have is from the 2015 issue of the Australian Commonwealth Specialists' Catalogue for King George VI, which includes information about the 2/6d emergency stamp.