Just for your info so you don't waste time looking for it, I have the Melo Gambit but it is not for sale/trade.
Black Cat is not a base sketch character, so if she did one it would have to be for the hinged sketches or an AP.
Reformed sports collector/seller, now strictly collecting non-sports sketches and loving it! - | - I no longer sell cards on eBay or through here. I will consider trades.
My sketch collection: http://sketchcollectors.com/gallery.php?user_id=727