I can't encourage this enough.

It was one of the most rewarding things I did in college. We launched a cubesat and used it to capture images of the curvature of the Earth and measure the Earth's magnetic field. The work to build the cubesat was tough, but extremely rewarding.

Edit:

Check out http://www.nasa.gov/offices/education/programs/national/spac... and see if you can find a local Space Grant program. They'd more than likely be able to either get you the resources or point you in the right direction to get going.

We launched ours via a ballon which had the cubesats attached to it. We needed a micro-controller (even easier to find now) a camera and our sensors. All very obtainable. I think the most expensive thing was the magnetometers which ran $80 a pop.

While it's still very cool, hanging a sensor off a balloon in the upper atmosphere isn't quite the same thing as launching a satellite into orbit (by about 8 km/s).