Western Sydney the cheaper but totally depends where you work and what suits your sitution. Western 'burbs like Lidcombe, Auburn, Parramatta and Homebush have gone up heaps lately. I'd go further West if possible. Bigger commute usually but more affordable as a whole. Carramar, Mount Duritt, Lakemba, Warrick Farm, Cabramatta and Liverpool. Places cost somewhere between 300k-450k. Those suburbs are only 20–40k away from Sydney CBD which isn't too bad really. Goodluck!