they still have a ridiculously archaic payment system in that department.

Oh absolutely -- George, who's been there for a century (literally), writes down one's purchases and prices on a slip of old parchment, and then one takes the parchment and one's purchases to Margaret at the door, where one is checked for charms, curses, and stray grimoires before any money is tendered. They prefer old money, of course. :)

Thanks for reading!