So she pulls out a koban, which is obviously a dangerously pricey item by modern standards, being worth like 600 bucks just for the gold content, and can even reach up to several thousand dollars depending on condition and age and such. But the thing is, it's also an insanely large amount of money by Edo era standards. It's equivalent to one ryou, which was like, enough to feed a person for an entire year. I feel like even rich people probably wouldn't have brought one as pocket change when they go out on the town.