Last weekend I attended the Williams Arizona Hamfest. Each year the Arizona Near Space Research group does a balloon launch. The instrumentation includes APRS trackers on VHF and UHF and Amateurs track and recover the remains, after the balloon bursts and the equipment falls to earth. They also had ATV!
I use an Icom IC2AT handheld for the radio. It is rugged, has no pl therefore inexpensive on ebay and has thumb wheel switches to set the frequency. The balloon was set to it's own frequency because of the wide coverage due to altitude. I removed the plug from the mic jack to prevent transmitting on the balloon frequency. Next time I will have a second tx to send my track on 144.390.
The balloon reached an altitude of some 92 thousand feet before bursting and traveled about 28 miles to the West of Williams, near Ash Fork. The FAA is notified ahead of time and kept informed of the balloons location.
The Nuvi did a great job of keeping track of the balloon and directing me on unfamiliar roads. Once the route it directed me was only a gate into a field but I have gotten used to its' foibles.
Depending on the terrain, some transmitter hunting skill might be needed to locate the instrumentation package.
More information is available on ansr.org. There is a kml file there for ANSR-76 that has a really neat Google earth file which shows the altitude as well as the ground track!
What do you do with your Nuvi/Tracker?