A friend of mine at work traded in his minivan, and somehow in the process ended up with a Toyota GPS unit that he didn't need for his new ride. This was way back around 1994/5— the olden days when GPS was still fairly new, expensive and exotic and hadn't been unlocked to its current precision.
I managed to hook up the Toyota GPS unit to the cigarette lighter in my Probe for power, and used a bunch of cable adapters to interface it to the serial port of the cradle for a 512K U.S. Robotics Palm III for display.
I used an old Logitec parallel port hand-held roller scanner to scan long black-and-white stripes of maps, then stitched them together on my computer. Then the stitched maps were loaded into the Palm as graphic files. With some software I found God knows where, I could drive to a known location near one corner of the map and mark it on the Palm III, then drive to another known location at the opposite corner of the map and mark it on the Palm III. Then the software would scale the map image and scroll it so the map would follow me as I drove around.
Each map file covered about 50x50 miles, which was plenty for getting around the medium-sized metro I lived in.
It was a free GPS. No directions. But if I got lost I could pop the Palm out of its cradle and look to see what was around me.