I knew I'd come across some somewhere in my web travels - you can get them all from
this site - American and probably hideously expensive, but you could probably bring in enough to sell some to pay for your own.
There's
bubbaearth.com.au but seems only their cotton is organic, not the hemp, and they don't have bamboo (I could be wrong though).
The other thought I had was to try the DIY section of The Nappy Network forums, there may be some people on there that know where to get it from...?
If it's for inserts you could try chopping up towels for the cotton, if they're not too thick?