Sheinside offers its Sheinside Women's Long Sleeve Slim A-Line Dress in Navy for $26. Coupon code "SAVINGS33" cuts it to $24.46. With free shipping, that's $12 under list and the lowest total price we could find. It's available in sizes S to XL.
Note: Uncheck "Add Shipping Insurance to your order" during checkout to remove the 99 cent fee.