Have you registered your copy of The Witcher 2 yet? maybe it's time to think about it given that registered users will have access to all of the Witcher 2 DLC for free and who doesn't want free stuff to add on to their game.
Developer CD Projekt RED answered Witcher fans through Gamestop's Facebook which revealed this information
"Let us announce that all our DLCs will be FREE," and also mentions that "If anything will be for purchase, those will be expansion packs. First DLC (side-quest called "Troll Trouble") launches together with the game release."
There is no information on how much content will be made available or how long to wait for it, but given The Witcher 2 has only just been released there should be enough to do for now until you run out of content.