Based on the median Perth rental figure given at $330 pw and the...

Based on the median Perth rental figure given at $330 pw and the median house price of about $460,000 that would be about a 3.7% gross return. Take out your expenses and you would be out of pocket about $500 plus pw (if you borrowed the lot and are paying about 9% p.a. interest). With inflation at about 4% and growth rates now minus (read this weeks paper) it doesn't look like a very good investment.

You could always sell your house in put the money in term deposit paying 8.5%.