Garmin designed the perfect GPS about ten years ago, and it hasn't been bettered. This is the most up to-date version before they decided to switch to colour screens and being far too clever for their own good.
I bought it as a backup GPS for a trip that never happened (now THAT was a summer!). As a consequence, it's sat unused in a drawer and has only been switched on twice.
Runs on AA batteries (important!)
Black and white display you can read in sunlight