If the G Shock is too expensive and you do want colorful flair, regular Casio Illuminator Digital Watches can be had at some Walmarts in a variety of colors. Walmart has them for only $18.88.
This World Time Illuminator is often seen in stores for about $24, but Kohl's had it online for only $19.96. As you progress through timezones, the areas affected are darkened on the world map at the 9 o'clock position. I think this has to be one of the coolest inexpensive digital watches on the planet. It's a lot of watch for less than $20.
For an even cheaper watch deal, check out this bargain basement Casio!