It won't just be $500 a week flat - like mentioned before you will have to add in rates, water, maintenance etc - but you also have to cover potential interest rate rises.
If $500 a week is what you can afford, I'd look at what repayments of maybe $400 a week will get you.
It also depends on what kind of house you want. I didn't mind an older house (cos I like them better anyway) that needs some updating and now I have a firm foothold in the market that will springboard me further alot quicker than if I had waited and saved for 'the perfect' house.