Not all magical retailers are in wizarding districts like Diagon Alley or Hogsmeade. For instance, there’s a shop on the Canterbury high street (near Hermione’s home) called "Pure Magick" which appears to Muggles to be a new-age store, but actually has a back area that carries real merchandise for wizards. This sort of thing is actually pretty common, with dozens of little magical businesses like this hidden throughout Britain.