Hey, anything's theoretically possible, but nobody's ever won that bet in human history. I would recommend the book "Voodoo Science" by Robert Park, specifically his discussion of Podkletnov's "Gravity Shield" and how NASA (yes, NASA) blew over a million dollars on it in 1999 before "discovering" it didn't work, even though all the physicists in the world had already been ignoring the man's "discoveries." In other words, NASA doesn't have a good record in this department.
By the way, if you create an anti-gravity device, you can use it to create a perpetual motion machine. That should tell you something right there.