@tyme @Shaz51 @Judi9877 @Snowie @rav3n @Harmonium @MJG017
I thought that I would share with you, some coins that you could get in your change, that are worth some money. For a more in-depth listing of error coins, go to https://www.australian-coins.com/error-coins/ or https://www.coinsandaustralia.com/coins-errors-varieties.php
Some Australian 1 cent coins are valuable, particularly those from 1968 due to their low mintage, and 1966 Perth-minted coins due to rarity and manufacturing difficulty. Value depends on the coin's year, the mint it came from, and its condition, with coins in uncirculated or mint condition being the most valuable.
The most valuable Australian 2 cent error coins include those with missing "SD" initials, which can sell for hundreds of dollars in excellent condition. This is what you are looking for. These days you can buy bags of 1 & 2 cent pieces, if your interested in trying to find error coins. I know I have at least one of the missing SD coins, but I am not sure of what condition it is in.
2c Missing SD Initials
The most valuable Australian 5 cent error coins include the 2007 Double Headed 5 cent coin, which has the image of Queen Elizabeth II on both sides, and the 2016 Alien Variety 5 cent coin, known for its antenna-like protrusions caused by a die clash. These are considered exceptionally rare and can be worth thousands of dollars depending on their condition.
5c Double Header
5c 2016 Alien Variety
The most valuable Australian 10 cent error coins are generally those with rare minting errors like the 2000 $1/10c Mule - I will show this in the $1 errors (an incorrect die pairing resulting in a thick rim), rotated die errors from the 1966 London minting**, or clipped planchet errors** (like the 1981 curved clipped planchet). While error coins can fetch significant value, their worth depends on the rarity of the specific error and the coin's condition, with values ranging from hundreds to potentially thousands of dollars for the most sought-after examples.
10c 1966 Rotated die error
10c Clipped Planchet
About half of the Australian 1966 20 cent coins were struck by the Royal Mint in London. For some reason one of reverse (tails) dies used in London was damaged and touched up resulting in a distinctive ‘Wave’ on the baseline of the 2 on the reverse of the coin. The so called ‘1966 Wavy Baseline 20 cent’ is the most sought after rare Australian 20 cent coin. Why? Because even a banged up one that has been circulating for 55 years can still be worth a couple of hundred dollars. If you’re really lucky you might find one in pristine condition in an old coin collection or money box, and that 1966 Wavy Baseline 20c could be worth $2,000 or more. How do you know if you have one of these rare 20 cent coins? Firstly your coin must be a 1966 and secondly it must have the distinctive Wave on the baseline of the 2. Checkout the image below, with the rare 20c you’re looking for on the left.
20c 1966 Wavy Baseline
The most valuable Australian 50 cent error coin is the 1988 double-sided coat of arms coin, with some examples selling for close to $15,000. The Millennium 50 cent coins for 2001 can be valuable if they have an "incused" (sunken) flag on the Australian coat of arms design, with prices ranging from $20 to $250. 1979/1980 Double Bar Error. These coins feature a die that was used twice, creating a thick double bar on the coat of arms instead of the normal thin one. Depending on condition and specific auction, they can sell for over $100.
50c Double Coat of Arms
50c 2000 Incused Flag
50c 1979 Double Bar
The Year 2000 $1 / 10c mule is probably the best known and most desirable $1 error coin. Dedicated coin noodlers have been finding them since 2003. Mules found in change have been sold for more than $2000. However, these were fantastic quality coins found way back in 2003 or 2004 and those found today might be worth $300 or $400.
$1 2000 Mule Coin
You should also keep an eye out for a gold $1 coin that has a rotation error making it worth as much as $350
$1 2001 Rotated Coin

The rarest and most sought-after $2 coins, such as the 2012 Red Poppy and 2013 Purple Coronation, have become valuable treasures for numismatists, fetching high prices on the collectors' market.
2012 Red Poppy
2013 CoronationHappy hunting coin collectors