An Australian 1981 Two Hundred Dollar coin (Royal Wedding), uncirculated and in absolute mint condition could fetch up to $420 AUD.
There were 77,890 minted.
Any valuation presumes that the coin is in the original packaging and remains in mint condition.
A reputable coin dealer will be able to give a more accurate valuation.
The Australian Dollar had not yet been floated in 1981 and was tied to the US Dollar. In 1981 One Australian Dollar was equal to One US Dollar. One Dollar AUD in 1981 had the purchasing power of about $2.85 AUD today. One Dollar AUD in 1981 had the purchasing power of about $2.64 USD today. NOTE - This historical conversion is the result of many calculations and considerations by a purpose designed program for which I can take no credit. The resulting answer should only be regarded as an approximation.
Maybe a couple dollars if it's in uncirculated condition.
Unless it's uncirculated, $1. Nearly all U.S. bills dated 1969 and later are only worth face value.
$1 bills from 1969 and later are only worth $1 unless they are in uncirculated condition.
In circulated condition, it's only worth face value. Uncirculated, it might retail for $110 but a dealer will pay close to face value if buying.
Both of these coins are still potentially in circulation. Unless they are part of a Proof or Uncirculated mint set or are individual Proof or Uncirculated coins and in absolute mint condition, they are worth 50 cents and One Dollar respectively.
The value of a 1981 US 1 dollar bill in circulated condition is typically its face value, which is $1. If the bill is in uncirculated condition or has a special serial number or printing error, it might have a slightly higher collector's value. It is best to consult a currency specialist or collector for a more accurate assessment.
As of 12/2009, the average retail price of an uncirculated 1981 $20 bill is about $22. Unfortunately 1981 is too new for the bill to have any significant premium attached to it.
Such a coin would have been issued as part of a mint or proof set. Any value would depend on the metal it was struck from and the design of the coin.
All circulation 1971 and later halves are made of copper-nickel, not silver, so they have no added value if you found it in change. A nice uncirculated 1981-P half might bring $1 to $8 depending on quality. A 1981-D would be $1 to $12.
20,000 dollar
Despite being over 30 years old, so many were printed that they have almost no additional collector value unless they're in uncirculated condition. Even then, you might only get $21 or $22 for it.