Natasha Romanova or Black Widow is a hero of the Marvel universe but it was not always like that. When the character appeared for the first time, in the comic Tales of Suspense #52, the Black Widow was a Russian spy and the antagonist of the hero Iron Man. Later she deserts and becomes a member of S.H.I.E.L.D. and after that a member of the Avengers.
In the LEGO world, this minifigure appears in 2 versions always related to the Avengers movie. The version that arrived to the Den appears in 3 different sets related to the second Avengers Movie, Age of Ultron, 76042 The SHIELD Helicarrier, 76050 Crossbone’s Hazard Heist and 76032 The Avengers Quinjet City Chase.
The minifigure has a lot of detail, both the the torso and in the legs. In the torso both the front and back parts are full of detail which makes it very close to the original character. The hair is not exclusive to this minifigure and it was used in several sets of other themes. However, a good choise for this minifigure.
This minifigures can easily be found in bricklink for $4. In my case it cost me a little more, around $6, which is still acceptable because of the detail of the minifigure.