I was just looking around eBay for bean bags to compare with the one that was posted earlier and came across this. They're made in Melbourne so I guess that's a good start. The one in the link is only a standard size so it is considerably smaller than the other bean bag, but they do have 600L bags listed on their eBay at around $69.99 + shipping. I've never dealt with King Kahuna but these look like they're quality made.
From the listing:
YOUR NEW BEAN BAG WILL TAKE BETWEEN 2 1/2 - 3
100 LITRE BAGS OF BEANS
EDIT:
Looks like the cheap white ones are all gone. There are still some other colours for $10 more.
EDIT 2:
Back in stock!
another beanbag bargain. rolls eyes
These guys seem pretty decent, however I think most beanbags are fairly cheap (until you get to the fancy ones).
Guarantee
• King Kahuna Pty. Ltd. guarantees this product is free from defects in material and workmanship for the one year from provable date of purchase