Currently at @edigrocer we use Allianz's "Public and Products Liability" small business insurance which costs us ~$50 a month.
Technically at the moment we are still a Sole Trader and will have to reassess when we move into co-operative status (fingers crossed for that happening in the next year!).
We also tried looking to the most ethical insurance we could find, but kept hitting walls. Allianz did come up in a few (self written) articles, and so we went with them. Actually it worked out that we approached our co-op bank (Credit Union of Australia) if they had any insurance that would work, which they did! ... it just happened to be underwritten by Allianz. All full circle.
Let us know if you find anything better! Good luck!