Amazon currently has some nice deals on Pro Trek PRG-600 watches. These are the most affordable options for a Tough Solar-powered Casio watch with an analog-digital display and the Triple Sensor (altimeter-barometer, compass, thermometer). The PRG-600 series also features a high-contrast STN LCD display and 100-meter water resistance.
Pro Trek PRG-600-1: With black resin band.
Pro Trek PRG-600YB-3: With green cloth band.
Pro Trek PRG-600YB-2: With blue IP bezel and blue cloth band.
Pro Trek PRG-650Y-1: With luminous inner band and Neon Illuminator black light.
There are also more Pro Trek deals on the PRG-330-1A, PAG240T, and more.