Casio M5610U with a metal mod I picked up for $99 and I love it! Pick up and go with never a care for durability or accuracy. World time across 5 presets, that you can swap back and forth with your home time at a press of buttons, solar powered, and radio receiving for auto updating of time and date.
What's your cheapest watch in your collection?
Timex MK1 40 mm with an aluminum case and time only. Cost less than $20 on Amazon. The funny thing is it has an acrylic crystal and soft aluminum case and only 30m of water resistance. I wore it when I used to do land survey work. It got rained on, knocked around, dirty, and generally beat on. Still works great.