"For the extra fabric and labor involved, I'd say two silvers," Teren decides. It's not as much as she would charge for a new dress, but still more than basic alterations. "We might as well do your measurements now, while you're here."
Her measuring tape is right on the table beside her, having seen a lot of use today, and she snatches it up and gets to her feet. "Arms out straight," she commands, and assuming Hermione complies, goes through the full measure-taking process with an almost military level of precision and efficiency.