http://users.htcomp.net/slashv/ http://www.hartsaussiestockdogs.com/Two aussie breeders, dont know them personally or seen there dogs.
In my limited experience with cowdogs, you will have a easier time finding a border collie or kelpie,that works, unfortunatley heelers and aussies have been bred mostly for looks lately , not saying all. The ones that have been brought here for training didint have the drive to make working dogs. Find someone that is using the dogs like you are going to, watch there dogs work before you get one from them.