[DampRobot]

A friend from Barn2 Robotics and I did something similar over the summer. Like the Canadians, we mounted some cameras and electronics (a GoPro, another camera, a SPOT tracker, and a prepaid cell phone) in a styrafoam box and flew it.

We ended up with some pretty cool video, and estimated that we made it to about 100,000 feet before the balloon poped. Take that, Canadians! We estimated our height based on the size of objects on the ground, as GPS is disabled over a certain altitude.