Harley Quinn - Batman Arkham City
I've always been a believer that cosplay is not merely about making your costume. It's about love of a character no matter what your crafting skill level is. Costume Supercenter sponsored a costume I have (honestly) been way to lazy to make myself. I wrote a review on it here, as well as a make up test using one of their kits. Below is a gallery of images taken to showcase the costume out of the box without modification.
Just as I mention in my review there are VERY simple things that you can do to make this costume even better all with things you can most likely buy off amazon.