I wouldn't really know what a ridiculous borrowing amount would be, as I don't live in Sydney and its all relative I guess - its only a ridiculous amount if you cannot afford to repay it or have any kind of life because the mortgage costs so much. What is a ridiculous amount for one person may seem perfectly reasonable to someone else. But I think that as long as you have your budget worked out and you can comfortably afford the repayments, remembering to factor in the possibility of interest rate rises in the future - and they will rise, its just a question of when - then you *should* be ok. Good luck with your new home!