The Seiko is a great choice. In the price range,and wanting an automatic(ie non battery) you might want to check out eBay for one of the auto Stocker and Yale milwatches. If I recall correctly they are pretty plain, but should also cost less than $150, and they have the Luminox-style tritium hands and markers, which give off a great glow.
You might want to check out Military watch Resource (
www.broadarrow.net ), too. I think Bob has some of the auto S&Ys and Marathons (another mil watch) for sale at great prices.