Charlotte Russe cuts an extra 50% off a selection of women's dresses. (Discount is applied in your cart.) Plus, take an extra 10% off orders of $75 or more via coupon code "10OFF75". Shipping adds $5 or get free shipping on orders of $50 or more. A couple of best bets:
Revolve offers the Isla_Co Women's Miss Totally Dress in Black & White for $56. Coupon code "TULIP" cuts it to $50.40. With free shipping, that's $30 off list and the lowest total price we could find. It's available in sizes XS to L.