Yeh you're right actually, been having a closer look, it is pretty expensive in the Nedlands area

.
I think students can only afford the cheaper places (they are also pretty crappy

) because they often have 4+ people living there paying the rent, which would definitely take some of the sting outta it. I would guess with a family and 1/2 people paying rent it would be pricey.
Have a look at some of the bus routes that go near by. I think the public transport system isn't perfect, but it is nowhere near as bad as people make it out to be.
Could also have a look at places along the train line. I *think* (never done it) that it isn't too hard to get to the uni from the trainstation in the city.