If they want to stick you with the cost of repair, get out there and do it your self. It's not too difficult to fix and can be done with the engine in the car. You might have to lower it, but it's all doable and for cheap.
This is coming from a self proclaimed klutz that did it him self.
http://forums.pelicanparts.com/porsche-911-technical-forum/595309-playing-oil-leak-detective.html