I'll add to the Perth, WA side I do quite a lot of fish store exploring, perks of being your own boss
Some may already be on the list, but may have actually moved as well. I've found that most good places are north of the river...I'm a southie
City Farmers - Chain pet store with your usual variety of goldfish. I have come across some Ranchu, but not very HQ as a lot of them had kinks in their backs or were most probably hybrids (mixed with Lionhead). I frequent the Willetton store and if you ask nice enough they'll let you know when their new shipments are coming in, or you can order some.
171 High Rd, Willetton WA 6155
3/378 South St, O'Connor WA 6163
Pet Barn - Chain pet store with the usual variety. Friend sent a complaint to them about the state of the fish tanks. A lot of dead and unhealthy fish. Hopefully they'll rectify this soon!
248 Leach Hwy, Myaree WA 6154
Unit 2/816 Beeliar Dr, Success WA 6164
Pet City - Small chain pet store with the usual variety, but now and then you might find some HQ goldfish.
6/113 High Rd Willetton WA 6155
30/87 Armadale Rd, Jandakot WA 6164
491 Marmion St, Myaree WA 6154
Pet Magic - Chain pet store with the usual variety. Now and then you might see some HQ ones, eg. Shubunkins, Bristols, Orandas, etc. Went into the Bibra Lake one last week and they had a big Oranda/Ranchu in a tank (couldn't see cos it was high up and I'm short) looked like it was close to pine-coning from what I could see though EEP!!!
1/10 Discovery Dr, Bibra Lake WA 6163
8/1500 Albany Hwy, Cannington WA 6107
Perth Aquarium & Display Centre - Haven't been here for a while. Went when they were still in Myaree, but they've recently relocated. They have plenty of tropical fish, but not much variety on Goldfish.
Unit 9/48 Prindiville Dr, Wangara, Perth WA 6065
Aquotix - This is a family run business (I think) and they are fish specialists. This place is my usual stomping ground when looking for tropical fish/plants for my tanks and some accessories. They have a whole section dedicated to ponds, goldfish and koi. Wide variety of goldfish with mixed qualities. Staff are quite friendly and happy help if you ask the right questions
4/176 Bannister Rd, Canning Vale, Perth WA 6155
Vebas Aquariums - Also family run I believe. They specialise more in marine and freshwater fish (especially cichlids). There's a corner for goldfish and koi, with your usual variety, but not much compared to other places. I've had mixed experiences here where some staff were a little stand off-ish, some were friendly and others just didn't have a clue what they were doing. Accessories are cheap here though...
5/1 Zeta Crescent, O'Connor WA 6163
Living Ponds - I found this to be a quiet place, but they have a large range of aquatic plants for the aquarium or pond. They have a section full of goldfish and koi! A good variety to choose from or to just oggle at.
363 Shepperton Rd, East Victoria Park WA 6101
The Bird & Fish Place - A place that's not hard to miss, just look for the dinosaurs. Went to check this place out one afternoon and came home with my Fantail, Sago. They've got a variety of tropical fish. There's an outdoor area where the goldfish and koi are. They have a lot of Calico Fantails, Comets, Moors and Shubunkins. I still can't get over all the animal statues though...
12 Lewis Rd, Wattle Grove, Perth WA 6107
Woodvale Pond & Lily Farm - I love this place! They have plenty of koi fish here, and big ones too! But yes, they also have a variety of goldfish too As the name says, they have an abundance of pond/aquarium plants. The staff are really friendly and really helpful too. Also, it's a good place to just go and oggle at the fish.
26 Woodvale Dr, Woodvale, Perth WA 6026
That's all for now. There are a few other places I have yet to explore and when I do I shall add them Hope this is helpful to those on the west coast!