Your near space project will be a disaster if you don't know where the payload lands. The easiest way to track the flight is with a GPS receiver. Not all GPS receivers are equal, though. Some receivers can track 30+ satellites at a time, report the position 10 times a second, and output the raw data from the satellites. We aren't making an unmanned aerial drone, and even if we were there are only 12 GPS satellites in view of a hemisphere at one time...don't get suckered into buying an expensive GPS because the numbers are impressive. The one important thing is to get a receiver that can operate above 60k feet altitudes. Many receivers stop working above that altitude due to international export restrictions and what not.
For my projects I have used the GS407 receiver (http://www.sparkfun.com/products/9436
). This is a small receiver with a helical antenna that gets great reception. The U-Blox chipset can interface with the U-Center software to set all the device parameters and update the satellite almanac for faster startup times (http://www.u-blox.com/en/evaluation-tools-a-software/u-center/u-center.html). Using U-Center you can also update the "dynamic platform Model" which allows this receiver to operate above 60k feet. You must set the dynamic platform model to "Airborne < 2g" or higher to operate above 60k feet.
I'll discuss how to change that setting after we have the GPS and radios connected.
For now all we have to do to the GS407 is solder 4 wires on. In the picture you can see that the serial communication comes out of pins 3 & 4 of the U-Blox module. Pin 6 is VCC or power and pin 14 is ground, which you also need as a reference for the serial bus. Solder a wire to each of these pins, you should be able to do it without a microscope using 30 gauge solid core wire. If you use 4 different color wires you'll make your life easier, too. If you feel nervous about soldering these wires you can buy a breakout board (http://www.sparkfun.com/products/10496
) for the GS407 that will provide slightly larger holes to solder to, but you're still going to have to solder.