Hi ideas-woman-garage-sale-guy,
Welcome to India! it is great to know that you daughter wishes to wear Indian costume for her Formals. I searched on ebay.in for things that might suit your requirement, I came up with this list:
Ghagra-Choli and Lehengas
Some products in this link are very reasonable. You will need to check with the seller if they wish to send to Australia.
The head jewellery is called 'mang tikka'. If you do not find a piece of your liking (becasue I dont think there are many listings for mang-tikka), you can ask any jewellery seller to list it. Most jewellery sellers will be able to source mang tikka for you.
Bangles and Bracelts are beautiful jewellery pieces. At tiems they have some ritualistic significance. For example, in my community, Red and Green colour bangles are worn by girls who are about to get married. However, most of the times, they are fashion acessories. They look cool, they keep on jingling and make sweet noise. I found this interesting article on the same, you might like to read this: http://www.hinduonnet.com/thehindu/mp/2003/01/13/stories/2003011301200200.htm
Do let me know if you were able to find the right dress and acessories for your daughter.
Cheers!
Sapana