Go to somewhere like Big W - they have packs of party favours. Girly ones with necklaces, bangles etc. More neutral ones with little toys, parachute men, etc.
Lollies - you get bulk packs of the little pack of lollies (gummi/trolli type). Things like freddo frogs, good for the little ones to eat. Lollipops.
Just a hint, when filling the pinata, don't put everything in the pinata. Keep some to the side. It's handy in case you have a shy child who holds back from the rush when the thing breaks, and then ends up teary because she doesn't get anything.
Or be prepared to re-distribute the loot if the bigger kids end up with overflowing bags