The Illustrated Dune and The Dune Trilogy are long out of print.
Try Second hand bookstores or Ebay.com
paid $5 for my copy of The Illustrated Dune and i've seen The Dune Trilogy for around $5 on ebay so
use that as a guide to what price you should be paying
new Illustrated Dune is only available in the UK at the moment. There are differences from the original. Gone
are the Black and White drawings but there are a couple of extra coloured prints. This new version is only published in hard back