Groupon offers the Undergirl x DC Comics Women's Anatomical Sleep Set in Wonder Woman, Batgirl, or Supergirl for $19.97. Coupon code "JUMBO3" drops it to $17.97. With $3.99 for shipping, that's a buck below our mention from two weeks ago, $32 off list, and the lowest total price we've seen.It's available in sizes S to XL, although not in all size/style combinations. Coupon ends January 21.