I'll try!
This must be the second oil version. It was commissioned by a man who made his fortune in coffee, which seems apt as the picture looks like someone who has had too much of the stuff. Not as good as the first version, which was painted to capture the artist's own feelings at that instant.
The picture just captures angst so well ( which may be why students often have it as favourite print!) The painting represents that far better than any more accurate, photographic, rendering of the subject would ever do. Munch himself was a disturbed individual when he painted it and graphically expressed his own state of mind.
If billionaires want to compete for such a significant work, the only example out there, well, the hammer price will be in the many millions.
What is a real mystery is why any Picasso is worth as much as $65 miilion (see link). Picasso never conveys any emotion through most of his work. Mind, if you like ceramics of goats or matadors, he made some good pottery!