Two MIT students launched a digital camera in a beer cooler with a helium-filled weather balloon and took thousands of photos over five hours from space. After the balloon burst and the cooler fell 18 miles to the ground, they tracked the GPS-enabled cell phone they also had in the cooler and retrieved it. The total cost of the operation was $148. They plan on selling kits for $300, including materials for $150 and instructions for $150.
WIRED article here.