I think Red Hot Design in Freo does plastisol, but I find their prices far too high. Anyway, if you want to check them out, here's a link:
Red Hot Design, Screen Printing Perth, Western Australia Clothing Design and T Shirts, Aboriginal Artwork
My findings are that there's not much in Perth in the way of wholesale supplies for people wanting to custom design and retail their own t-shirts. I get my stuff screenprinted in the US by Circle R. Excellent quality and cheaper than having it done by Perth screenprinters who mostly use Ramo blanks - Circle R can get you virtually any American brand blanks you want at far better prices than we can get in Perth, even including freight costs.
But if you're after plastisol transfers, maybe you have a heat press and intend doing your prints yourself, in which case Circle R may not be the best bet for you. I'd still look at sourcing plastisol transfers and t-shirt blanks from the States, though...certainly worth researching and comparing prices in the first instance. I'm confident you'll do far better from the States than through Red Hot, anyway (especially with the current relative strength of the AUD compared with the greenback).
Cheers
plastisol design in Perth 
