I gave my son a flight in a one seater(made into to a 2 seater and he sat on my lap) for his 10th birthday. it was...ummm awesome. I sat on a milk crate, i'm not kidding.
give him a flying lesson, they're not expensive.
My boss got a ride in an Indi car for his 60th from his wife.
If you're strapped for money this year, how about a model airplane (Michaels in NY has them, I don't know if by you they do).
get him a telescope, he can be kept busy for hours with that.