He's right, the number the Captain gives isn't small. They COULD afford it, though they don't have that much ON them at the moment. Of course, there's always lying.

"We could pay on delivery," Kreyu adds. "That much in gold is heavy to carry through the air." She tilts her head. "Our home is north east from here, a day's sailing." NOT the direction where they came from, Kreyu must have another location in mind.