Another alternative would be to go and check out the OpenTracker+ from Argent Data Systems. You can buy it as a kit, a smd version that has the whole thing in a 24 pin DIP, or just get yourself the parts and the PIC and flash your own. And the code is open source so you can tweak it as you like! They have firmware versions where you can make a weather station or a TNC ( Terminal Node Controller), which is just a fancy name for a modem in HAM radio.
-Chris