The shoes are not cheap here; expect to pay more than 10,000 (sorry, accidentally wrote 100,000 which is incorrect, thanks lostinube!) on average. But they do have occasional sales.
They have a shop specializing in large sizes in Ginza also. Similarly priced to Queen's 卑弥呼, but perhaps a bit better quality.
In addition, 0101 department store (Marui) has a 01 MODEL floor on the 7th floor of the main building specializing in large shoe sizes for ladies. 新宿マルイ本館