I don't know what part of Qld you live in, but if you live in Brisbane get in touch with the City Council and they'll be able to help you with places that might sell them. Or you could look in the white pages under worm farms. They mightn't have silkworms, but could probably point you in the right direction.
Not Victoria, but certainly the advice was sound.
Hope this helps out ! Also, try any dragon rescues, and the zoos. I'll bet they have a source
Janie.
Silkworms are seasonal down under, we don't have a year round supplier for them. There's just not a big enough market for them to make a business like that commercially viable (wish it was). Anyway Amazing Amazon in Glen Waverly on Springvale road has just started stocking them may be worth giving them a call before you trek out there though as it is only the start of the season.