How much are you sued for illegally downloading films?

Short answer: 1

Long answer: It would probably not be in the best interest of a legal firm to push for proceedings for a single instance. But the law is quite clear that a single illegally acquired song, movie, book, TV show, videos etc "digital media" is violation of the copyright laws and is prosecutable. Even the possession of a partially downloaded copyrighted item that you don't have a legal DRM (digital Rights Media license) for is subject to prosecution.