I just hope your not the kind that go out and buy every single DVD or new effect that comes out and all the decks of cool looking cards.
Like everyone else in the thread.
Personally speaking, I would grab a copy of Mark Wilson's Complete Course in Magic and maybe Jay Sankey's Anytime, Anywhere. You should be good to go with that alone. If you really must purchase a single trick DVD, Ghost Bills by Andrew Mayne kicks the living hell out of most any latest and greatest card "miracle".
Those are the most general recommendations I can give. I can't get more specific until I know more about your performance style.