SheIn offers its SheIn Women's Sleeveless Backless Flare Dress in Black/White for $12.50 with free shipping. That's $19 off list and the lowest total price we could find. It's available in sizes S to L.
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.