He ignored Castiel's argument entirely, instead focusing on the questions. Those were much easier to answer.

"A knife made out of iridium," Crowley said mildly, though he did drop back next to Castiel to say it, so no one else could hear, "in exchange for a soul. And some money." The demon shrugged a shoulder lightly. "I heard he was in possession of one, so I decided I wanted it. And as for what I'm getting now -- "

He patted his hellhound lightly.

"Nothing of great importance."