That Figures who Double-Barrel Carol's inspiration is:
Travis Pitts has made the internet rounds for a while now. Double-Barrel Carol is so close to this Velma (while being nothing like any other zombie hunter of pop culture fame) that she simply must have been inspired by this piece. Which makes her even more awesome than without a reference source, if that's at all possible!
Now to find an in scale Scooby Doo figurine!