Your best bet is to contact the secretary of the Australian Shepherd Club (Mrs Sarah Green. Tel No: 01924 489859) and ask for details of reputable breeders.
There is also the other breed clubs secretary National Australian Shepherd Association or you could send a private message to Gabrielle on here and she may be able to assist aswell.
Anybody who doesn't know what soap tastes like never washed a dog- Franklin P. Jones Gill