There are a few types of island mats that can be found around Cairns. Authentic made, generally from PNG and the others are made in China and often made of some types of plastic, also found in some Asian/Chinese stores.
Bamaga Dreamtime Store in Earlville Shopping Centre generally stock both kinds of mats.
Crowtex The Island Store only stock the plastic variety in different colours and sizes.
You can purchase some of the PNG mats on some of the Torres Strait Islands especially when PNG peoples come to trade on the shores of the island for the day.