I know of a websight that had links to rodent breeders but all seemed to have expired in my state of victoria so where would I get rats and mice for pets ethically & yes I know to keep the two different rodents seperate?
If you're looking for a pet rat or mouse, try guinea pig rescues. I don't know how common they are in Victoria, but here in Queensland we've practically got guinea rescues coming out our ears, and every rescue I've seen also takes in mice and rats, and because murids aren't popular adoptive pets, they more often than not have a ready supply of them in all ages up for adoption.
Also normal rescues usually have them. Usually young too, I would look into buying from a rescue instead of a breeder. Will they have a big cage to roam in and lots of toys to play with? ( especially rats as they are pretty smart)