To be a unique thing I have no idea.
I trust in the knowledge of the members of the Forum.
Its all about the quality of the artwork, and whether they are complete or not. And hand painted doesnt necessarily mean they are more valuable than printed, theatrical posters, since it's also about the quality of the art (or lack thereof), the film title, director, poster condition etc.
Just guessing here but maybe a value of 250-500 each? (for those that are not the complete poster).
Its like those that sell part of a 3 sheet poster, 6 sheet or billboard size. The value is much different (less) than that for the complete poster.