I agree with Jim, I suspect lots of racers will have spectator tickets available.
However, I would like to throw a spin on this because that is what I do.
Mojave is an awesome event, run by a great team. As a competitor it really grinds me as I'm standing around for hours in the sun, all leathered up,
waiting for yet another freakn Piper Cub to do touch and go's.
And as a spectator, you may be a bit let down because you can't see anything.
What I would recommend is spectating at the Bonneville Salt Flats. It will be the coolest event you have ever gone to.
Not to mention Carmin's Black and White Bar in Wendover, on race nights it's the coolest bar in the world.