It would definitely have to be rent shared three-way between Ryan, Ryan's sister and Nathan (Ryan's sister and Nathan are in a relationship). Rents vary greatly in Rose Bay, the majority of 2 bedroom stuff on Domain is going for $550-$700 a week (managable if you've got 3 people).I think Ryan was living with Nathan Jolliffe, so maybe Nathan owns a place around there or they share the rent?
Ryan's parents live on the Sunshine Coast at Mooloolaba.