I don't know if there's been one especially for Magic: The Gathering, but I know there have been a few people who have made tarot decks for their own games. For example,
Mage: the Ascension Tarot is made for a roleplaying game. However, it was made by the company that actually made the game, not by a fan.
On the other hand, there have plenty of decks made by fans of a show or game, so I can't see why this wouldn't work. I myself played Magic YEAAA~RS ago. I've pretty much forgotten how to play, and long since given my cards away.
As for card scans, I just google searched it and it's your lucky day.
http://magiccards.info/ (That "browse" link takes you to a list of all the cards)
Good luck with deck creation. We here in the Deck Creation forum will be cheering you on. Looking forward to seeing your progress and your finished work!
~David