Try...
Link hidden: Login to view they have a good range of different styles in stock and they have a 5 star rating in the Salehoo directory.
Link hidden: Login to view they sell bulk lots of shoes so you would need to check if flats are included. 4 star rating in directory.
Link hidden: Login to view supplier of bulk lots as well so you would need to confirm what styles are included.
Link hidden: Login to view a large range of flats and pumps in stock. 3 star rating.
Link hidden: Login to view a variety of styles and colours currently in stock. 4 stars.
Hope these help :)