I don't see why you need to buy a gimmick to pull off this effect. The deck becomes un-examinable. In my mind, when you have a choice between sleight and gimmick, always go with the sleight. The upside, your deck is always examinable, the downside, you need to practice a lot. In the end, you will probably be better off learning sleights then buying gimmicks. There are many card risises in the book Expert Card Tecnique. My favorite is called the Witchcraft Rise. You don't move any part of your hands, but the card still rises out of the deck. It is completly improptu and can be done with a borrowed deck. The best part of this is that all fingers a visible and they don't move! Of coarse that is the same with the gimmick, but with this sleight, the deck is examinable. Of coarse, I am not telling you to stop using the gimmick, I'm just giving my opinion. You should do what you feel is most comfortable to you. But I would recomend learning the Witchcraft Rise. That way, you can compare it to the gimmick and see what you prefer.
EDIT: Another advantage of the sleight over the gimmick is the sleight doesn't break down on you.
