Demolition costs will be dependant upon what type of material your house is constructed of, size etc.
If you have a timber/fibro highset house, you may be able to sell it. If you have brick/asbestos etc you will have to demolise and dispose of it.
Don't forget to sell whatever useable items you can. (kitchens, bathrooms, showers, roof tiles, timber etc etc).
Make sure youget a couple of quotes as they can vary by thousands. All depends on how much work the demolotion co. has at a particular time.
Cheers
BUNDY