This Black Halo Jane Sheath dress with one-shoulder in black silk costs $390 at Ssense.com.
This LC Lauren Conrad one-shoulder dress creates a similar silhouette, minus the draping, but I think I actually prefer it: The shoulder detail is so festive, and the cut of this dress would flatter many figures. Great party dress, and it's only $45 on sale at Kohls.com. Love it.