Ending tonight, 6pm offers the Keen Women's Emerald City 3-Point Sandals in Slate Black for $19.99. Coupon code "6PMEU10120141028" drops it to $17.99. With free shipping, that's the lowest total price we could find by $40. They're available in sizes 7, 7.5, and 9.
Note that although 6pm pictures a different color, the color offered is Slate Black.