SheIn offers its SheIn Women's Halter Contrast Trims Hollow Swimsuit in White for $14.50. Coupon code "INST33" cuts it to $13.51. With $1.90 for shipping, that's $7 off 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.