Like everywhere in the world at the moment everything is on the increase. The Aussie dollar is currently at 97c against the greenback and so we pay just slightly more per yard than you do. Last year however it was around 50c and so we payed double. However that still worked out cheaper than in Australia for a yard of material!
Depending on your skill set and education (as with most countries) you are payed accordingly.
I have a quandry about buying material online though as I want to support local craft shops and stores in Adelaide but I just can't pass up such great quality fabric at what is a true bargin. I do still buy patterns, thread and attend classes at my local quilting shop which will have to suffice!