Places to buy Dunlop enduro or similar foam to replace in to couch

Hi all
My existing couch is unusually hard and may be cheap foam in it and has become very uncomfortable, and in true ozbargain spirits I am looking to replace the foam rather than replacing the couch. I started looking around for the best foam and found that Dunlop enduro was quite good from a sales person in a furniture shop :) however I can't find a place that sells them, may be my googling skills are not very good. Been to Clark rubber but only found a generic foam and that too very expensive $150 bucks for 1 seat which measures about 800 *900 *150mm. Which would cost me nearly$1000 to replace the whole couch which undermines the overall purpose, as the couch costed me $1800 brand new.
So I am being a tight arse and asking my fellow ozbargainers if you can point me in the right direction. I am based in Melbourne by the way.