Depends if you want to be near rail/public transport or not. And also if you want features such as a pool, relatively flat terrain (it's quite hilly in the North Shore), number of bedrooms, etc.
You could get a house in West pymble, East Roseville, North/South Turrumurra for under 1 mill. Most of the houses in lower north Shore (South of Chatswood) are either mansions or units/apartments.