Travel backpacks are perfect because they allow you be highly mobile while still carrying a lot of weight. Traditional suitcases and duffel-bags are inconvenient because they are difficult to carry long distances. Below are some tips to choose a nice backpack.
First, look for quality not just the lowest price. Quality is the most important. Look for bags made by Osprey, Kelty, Gregory, Deuter, GoLite, Mountain Hardware, and Arc’teryx (there are a few other good brands). The last thing you want to happen is a ripped backpack after your first bus ride. Second, choose the one with comfortable shoulder straps. Nice shoulder straps will make your journey much more comfortable. Third, do not full load your backpacks. Remember that you are going to carry this bag around for long periods of time. It is very important that you can handle your bag by yourself. Everything you need, including warm clothes, jacket and shoes should fit easily in a 60L bag; if you cannot fit everything in, you do not need a bigger backpack, but fewer clothes.
There are a lot of suppliers offer travel backpacks in Australia. Go shopping and get your suitable one.