1981 was an interesting year for varieties in the 20 cents coin. The main reason was that this coin was minted by three different Mints, namely, Wales, Canada and Canberra. The one that most collectors chased after is the 3 1/2 claw 20 cents minted in Canada. As they are minted for general circulation, it is hard to get one in UNC or better.
Here is a photo of an UNC one, have a look at the 4th finger of the right claw of the platypus.CV of the Wales and Canberra ones in UNC is AUD$3.00. The Canadian minted one commands a CV of AUD$150.00.