The Bryton link shows a Bryton Rider 100E GPS Computer @ $53.95. I have no endorsement. I've just read here that some like the Brytons, though I've never seen one myself.

The lowest cost solution if you already have a smart phone is an app like Strava or Cyclemeter and the phone in your pocket. You don't have to have cell phone service; you can do all the downloading and uploading required before and after the ride where WiFi is available. The next tier up would be buying a good mount to put the phone on the handlebar. Then the next tier up in cost is a dedicated bicycle GPS computer. BF opinions are divided on whether the phone or computer is a better choice regardless of cost.