This article documents a LEA-6T module build for general experiments.
The LEA-6T is an inexpensive GPS module (~$40 at time of purchase, but getting cheaper) that can supply raw pseudo range data.
The module above is supplied for use on UAVs of various kinds, and came complete with a plastic radome and cables to suit an APM copter. The module also contains a 3D compass (magnetometer) which is not used here.
Above is the internals of the module with a custom cable to pick up just the RS232-TTL signals from the GPS (and supply 5V). The connector is a 8pin Hirose DF13.
Above is a close up of the cable pinout.
Above is a FTDI Basic (as used with Arduino) and the GPS cable, again showing pinout.