Another source of cheap USB GPS units is outdated versions of Microsoft Streets & Trips. These ship with a simple TTL Serial GPS (a Pharos PB010
) connected to a Prolific serial→USB converter. Plugged into a Raspberry Pi, it creates a serial port spitting out NMEA sentences at 4800 baud. If you trawl the software clearance places, you can find these for £10-15.
One day, I'd like to try one of those small I²C GPS units meant for quadcopters with the Raspberry Pi.
‘Remember the Golden Rule of Selling: “Do not resort to violence.”’ — McGlashan.