I've never used one of these GPS modules, but it seems like you could build a board with the GR-10, the Sarantel P2 antenna, a PIC, and a small low-power 2 meter transmitter, and have a nice, very small APRS tracker.
I'm wondering what the challenges of that project would be. The reference design for the Sarantel antenna (http://www.micro-modular.com/docs/MN101 ... rantel.pdf) calls for a RF2370 amplifier and some inductors - could you throw a few SMD inductors with the specified values on a board and call it a day, or is there likely to be some tuning and testing required?
I'm sure I'm missing something here. Not sure at all about the design for the TX either, but there's a ton of info out there from ham radio guys so I'm sure something could be built. For example, the "MicroTrak 300" does packet encoding and transmission, but you have to plug in an external GPS.