Sheinside offers its Sheinside Women's Color-Block Half-Sleeve Flare Dress for $16. Coupon code "INST33" drops it to $14.85. With free shipping, that's tied with last week's mention, $7 off, 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 shipping fee. Also, it ships from mainland China and should arrive in three to four weeks.