SheIn offers the SheIn Women's Puff Sleeve Slim Dress in Navy for $16.65. Coupon code "DN35" cuts it to $15.98. With free shipping, that's $9 off list and the lowest total price we could find. It's available in sizes S to XXL.
Note: Uncheck "Add Shipping Insurance to your order" during checkout to remove the 99-cent fee. This item ships from mainland China and should arrive in three to four weeks.