DIY. Take two pieces of contrasting spandex and twist together in front and tie in back! I think you would probably have to sew the breast covering part together to keep your boob from being exposed but that might be it.
I dream of this outfit . . . open back with a beautiful Chanel necklace hanging down the back . . . heaven. It doesn't have to be a skirt and shirt combo, this would look great with a formal dress too.