For very reasonably priced accomodation in Perth (approx £30 pnpr) I don't think you can beat the City Waters Lodge in Terrace Road. Very close to the city itself, you can walk easily into the CBD and also to stunning spots such as Kings Park and Barrack Street Jetty. City Waters Lodge is basic 3 * accomodation but is very suitable for a family with both double and family suites available. They have kitchens which are fully equipped and also a laundry. The staff are very helpful and friendly and have extensive knowledge of the Perth area, their main office also doubles up as a tour centre where information can be collected on local attractions and excursions can be booked. The Lodge fronts onto Langley Park which runs alongside the Swan River and provides an excellent place to sit in the sun and watch the world go by. I have stayed there twice now and have been very happy with the quality of service I have received, I would be happy to recommend it to anyone. Further details can be found on their website: citywaters.com.au