I'd say, your best resource is your computer! Try using the various search engines for travel sites, and have a look at the Qantas site as well.
Qantas website will give you a good indication of how much an airfare will be. You can then try other sites, and make your own comparison.
Window seat, I'd agree with Gordon - sites such as ITN Website are helpful when you are searching for seat availability on flights around the world. You can build itineraries and they will price them (there's your starting point anyway).
For example, one flight might show the following:
F6 A6 J9 D4 U6 Y9 B6 H9 K6 M9 L9 S9 V7 O2
You may be unfamilliar with all the letters and numbers. However, it's simple - they are the different fares available (eg. F & A - First, J & D -Business, U - Upgrade seats in Business; Y & B etc - all the different types of Economy fares) and the number of seats - you will often see 9 or 4 (which means there are more than this available for sale, but only single digit numbers are shown on the site - some airlines show 4, some show 9). When it gets lower, it means there are only those seats available.
I've found this particularly helpful (thanks to thadocta for showing me)
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