Shoebuy offers the Aerosoles Women's Novol Idea Shoes in Grey Combo for $29.99. Coupon code "EMLPRESIDENT13" cuts it to $23.99. With free shipping, that's the lowest total price we could find by $10. They're available in sizes 7, 8, 9, and 10.

Of note, these are available in Black Combo in size 10.5 only.