Can I travel to Australia on a one way ticket?
There is no requirement to have a return ticket when you arrive in Australia.
However, some countries will not let you leave their country, on a flight to Australia, without a return ticket, if you are travelling on a temporary visa.
The airlines will know the rules that apply.
On arrival in Australia, the Border control officers do need to be satisfied that visitors, working holiday maker and temporary residents are intending to, and have the means to, depart Australia before their visa expires.
Immigration do suggest that you carry a copy of your bank statement to demonstrate that you have sufficient funds to purchase an airline ticket to depart Australia. It is not a mandatory requirement though.