Such a great question. If Pancakes count, I love buying their mixture that Pancakes on the Rocks at Beverly Hills use to make their original stacks. Otherwise I go to the supermarket. Donna Hay macaron making kits anyone? Yep, available at the supermarket.
Accoutrement in Mosman has amazing cake decorating tools. Those dyes that are thick and not watery, little sugar decorations, every colour of pre-made fondant icing you can imagine... It's a cake decorating paradise!
Cake Decoratin Central, in Castlle Hill ( they have store in Cambeltown too) -this is the place to find pretty much everything you need for any themed cake or party you can think of :) Tools, fondant ( pre made or ingredients to make it yourself), gum paste, sugar decorations, bakin pans ( in every shape you can think of ), great quality food coloring.... Staff is very knowledgable and helpful, if you need any advice. They also have an on line store, and great cake decorating classes. Super place for all cake decoratin lovers! :) As for ingredients : any supermarket will do, I personaly love making my cakes from scratch .