He was certainly prepared to tell her that he had enough on his plate that worrying about assuring the proper diversity in the library was rather far down on the list, and that she ought to have learned Gamp's Law of Elemental Transfiguration at some point in her first year, which would have told her that money did not simply appear out of thin air.
But as soon as she mentioned the Muggle section, he began to reconsider - not that it showed on his face. He held his stony expression until she had finally trailed off, and let the silence extend another moment or two. He was considering. Muggle Studies had been disadvantaged, to say the least, in the school's recent past, and it was only fair to bolster it a little - quite aside from which, he did not at all mind the thought of informing the relevant Professor that her resources had been expanded.
He opened a drawer in his desk, pulled out a pad of paper, and set his quill atop it, where it balanced and waited. "Cross-cultural understanding is, of course, of the utmost important, given recent ... events," he said, his words a little dry, as the quill began to write out a withdrawal. "I am not acquainted with the average of price of Muggle books. Will a few hundred Galleons suffice?"