We had a fantastic time in GSBC this year launching a kiwi -- you can watch the video here: https://www.youtube.com/watch?v=xFXJCUFYrZ0.
As a challenge to ourselves, other than a SPOT GPS and a GoPro, we tried to keep it as low-tech as possible. We used a styrofoam box for the payload, carving out a hole for the GoPro with a plastic ruler. To counterbalance the kiwi, we used a plastic bag full of water, and to keep the GoPro warm, we used another plastic bag full of water inside. With a fairly high heat capacity, this acted to stabilize the temperature inside the payload box and let the GoPro survive the freezing temperatures of the upper atmosphere.