Riddick's body language is pretty much never very open. But he isn't any more closed off than he usually is, at the moment, so that's a start. "Which one's more expensive?" is his follow-up question, coming with a wry smirk. He's been pretty much ignoring the "debt" he's wracking up by eating out so often, in part because he's curious what they'll do to make him pay, and in part because he just doesn't care.