Just search Google (or whatever search engine) for digital car compass or just Compass and you will find many. I have a plastic digital compass that shows barometric pressure, altitude (based off the barometer), direction by arrow and compass points etc. I have found it accurate and reliable, only needing recalibration if you let the battery get too low or it looses power from the cord.
On my bike I have a liquid filled car compass that works well enough for something about 25 years old that I picked off my garage shelf after almost getting lost in the rain one day in the country (easier to happen than you might think, OK, you can laugh, but it might happen to you someday!)
A liquid compass jumps around a lot but is good enough to give the info you need.
For a great compass, search for airplane compass's. I have seen a few that would be way cool on a bike.
the cheap compass's are about $15-30. A LOT less than a GPS if direction is all you need.