If you check Ebay, do a search on Palm GPS and you'll find hundreds of Rand McNally GPS modules for various palm-based palmtop computers for super cheap. These all tranmit standard rs-232 serial and in most cases their output is a standard generic code that you can intercept with even a Stamp and convert to useable iunformation. I got mine for about $16 US and it works great. You can order a GPS module on its own from Laipac www.laipac.com, but you'll need a separate antenna.