preposterously

This adverb carries a strong tone of disbelief or irony. It is used to describe something that is not just unlikely or incorrect, but so far removed from reason that it becomes comical or shocking. It is more emphatic than "ridiculously" and often implies a sense of indignation or amusement at the absurdity of a situation.

In terms of register, it is slightly more formal or literary than "crazy" or "insane," making it suitable for both written critiques and spoken commentary where the speaker wishes to highlight a stark contrast between reality and a specific claim or price.