I'll write the questions in English even though originally they were asked in Finnish.
Did you have a lot of money saved up when you left? Is Australia expensive and what kind of budget would be good to have when going there?
Australia is considered an expensive country, but that doesn't mean that you can't do things cheap. You just need to plan ahead a lot. When you start researching for your trip all the sites say to have at least 5000 dollars in savings when coming here, which is about 3000€. Personally, I've been using my money pretty well. I spent more than I had planned in Perth, and on this last part of my trip I'm doing more activities like diving, and maybe sailing? What I try to save on is food. That means a lot of noodles, less of the expensive stuff - like eating out. I also haven't been partying that much, so if that is what you would like to do here, I'd save up even more because alcohol is very expensive...
So I would say that the number one thing is to do research before you leave and really think about where you want to go and what you want to do there. I think that has helped me a lot.
I should also say that a hostel isn't the thing you should be saving at, especially if you're by yourself. Look at the reviews and if they're good (hinta-laatu suhde), then book it! You don't want to live alone at a crappy hostel, and be scared of living there.
Hope this somewhat helped. I don't really want to say how much money I had, but it was what was recommended.
How expensive are the hostels ? And the prices in general?
I've been surprised by how easy it is to get a good and cheap hostel here. The one in Melbourne was the most expensive one so far, and it sucked, so that even tells you to not always pick the most expensive one.
If you plan on going to Cairns, Gilligan's is the way to go! I would suggest downloading the app hostelbooker. Not only do they pretty much have all the available hostels in Australia, but also other places in the world!
Prices in general are OK. The alcohol compared to Finland is more expensive (can you believe it?), but the clothes are a bit cheaper, you just have to find the right stores. Food is pretty much the same and eating out as well.
Activities can get expensive, but in the end I would rather spend more money on a good trip, then be disappointed.
All in all, if you want a cheap backpacking trip, Australia is not the place for you. Then I would suggest you backpacking through Asia or even South America.
Even though Australia is quite expensive, I would still recommend it. There is so much to see, and definitely something for everyone. I love this place and I already feel sad about leaving it in a month.