In the Adelaide Hills Price Ranging is quite common.
Personally I don't like it, and most buyers feel uncomfortable when they see a property advertised like this. Its vague, and difficult to work out what a seller is asking for the property.
I recommend to sellers to always use a single price wherever possible as it provides transparency to what our objective is in the sale.
If you are looking at a property in a price range, try to disregard either end of the range if you can and go with your gut feel on what a fair offer would be on the property. In SA all written offers must be put forward to the owner by law, and at the end of the day the worst they can say is no and counter with another figure - now you know what they are really asking!!! :)