There *was* one called "Lilly Pilly Caterers" or similar that once did friday lunches out of the Warriparinga cultural centre in Marion. That project died a predictable quick death (though strangely, not for lack of customers as far as I could see) but the catering side of things might still be going... I know they got a lot of the ready-made Fielke products (pies and stuff) from the food distributors at Cavan, so maybe that mob know where they are, or can give you tips on who else buys from them....
Or maybe they bought from FGM? Same suggestion applies, check out:
http://www.andrewfielke.com/Distributor ... 0Jul06.pdf
Another possibility is to phone Warren of Tumbeela Native Bushfoods, Verdun:
http://www.visitadelaidehills.com.au/pr ... id=9004661
While Warren isn't a caterer, sometimes he hosts things at his place and/or definitely would supply caterers so may be able to shed some light...
Personally, depending on what you're caterering, I'd be inclined to purchase the wholesale stuff myself and go from there. FGM definitely sells to non-industry people if you can be blowed driving up to the boonies (relatively speaking)