Booking your flights in advance and also the same day booking makes a lot of difference in the fares that you will be charged. It is because when you book for the various destinations from Australia, you will be charged on the basis of a lot of factors that determine the flight facilities and benefits.
There is always an option for you to book your flight at the time when you need, but the situation becomes a little bit of different when you have strict requirements of the same day booking. It can be a hard to handle the situation and may cause you a lot more money as compared to the rates that are charged normally. You can find any flight or flights to Bali and also flights to Los Angeles or flights to Paris or to any other area where you need to go to the same day booking. But the fare will be higher in case you are going to travel on the same day flight or you have booked your ticket on an extremely crowded day when a lot of people have been trying to travel to a particular destination that you have selected.
You should always try to avoid same day bookings when you are on a budget and you need to travel to the popular places. Though its true that you can easily find cheap flights to London and also cheap flights to Los Angeles as well as cheap flights to Shanghai and cheap flights to Kuala Lumpur whenever you need, but the timing and the booking span matters a lot. Sometimes the planes are overcrowded and you may not be able to get the same day booking or in other case you will have to ay a lot more money to get the same day flight. If you are flexible in your timings, you can save your money and find cheap flight to various spots like cheap flights to Hong Kong or cheap flights to Beijing and cheap flights to Tokyo or wherever you need to go for like New York or London.
All depends on how you handle the booking time and the way you set up your destination with the right flight options.