Came across this 
The 10 Worst Silver Coins for Investment
8. Silver Australian Koala
5. Silver Australian Lunars
7. Silver Australian Kookaburra
"Like the Silver Koala, the Australian Kookaburra is produced by the Perth Mint and is legal tender in Australia. The Kookaburra has one unique distinction: it's the only legal-tender coin to change its design annually. Kookaburras have been minted since 1965; ironically the year that U.S. coins were debased of their historic silver.
New Kookaburras sell for about $6 over spot, just like Koalas. They are attractive coins, too, and make a welcome addition to anyone's collection. So why are they ranked below the Koalas? Because market demand for cute Koala coins is significantly higher than demand for Kookaburras. What is a Kookaburra anyway? The 2007 coin is already selling at a $3 discount to the new issues. Thus, Kookaburras, despite their rarity and legal-tender status, most certainly can lose non-silver value in a short time."
The 10 Worst Silver Coins for Investment
8. Silver Australian Koala
5. Silver Australian Lunars
7. Silver Australian Kookaburra
"Like the Silver Koala, the Australian Kookaburra is produced by the Perth Mint and is legal tender in Australia. The Kookaburra has one unique distinction: it's the only legal-tender coin to change its design annually. Kookaburras have been minted since 1965; ironically the year that U.S. coins were debased of their historic silver.
New Kookaburras sell for about $6 over spot, just like Koalas. They are attractive coins, too, and make a welcome addition to anyone's collection. So why are they ranked below the Koalas? Because market demand for cute Koala coins is significantly higher than demand for Kookaburras. What is a Kookaburra anyway? The 2007 coin is already selling at a $3 discount to the new issues. Thus, Kookaburras, despite their rarity and legal-tender status, most certainly can lose non-silver value in a short time."