With property in Altona there are two major factors the will determine price - Block size and location. The closer you are to the beach the more expensive. Ideally you should try to get property from the beach up to the railway line, but not past the railway. In that pocket you can pay anything from $550,000 - $2M.
About $850k for a decent block and pretty satisfcatory house but depending on what you want the range is probably $600k to $2M or so and townhouses are naturally cheaper and because of land size lots are going up!