A best bet is the OneHanesPlace One-Piece Glam Swimdress in Red (pictured) or Black for $37.99 plus $1.99 for shipping via the coupon code above. That's $17 off and the lowest total price we could find. It's available in sizes 10 to 18.
Spending more? Coupon code "475140" takes 15% off $75 or 20% off $100.