+1 for G-Shocks. Even though Casio rates the accuracy of it's $8 FW91 quartz watch at "only" around 1 second per day[1], many people observe 1 second per month with others observing 0 seconds after 2-3 months. This makes it more accurate than almost all mechanical watches in any price range.

[1] http://support.casio.com/storage/en/manual/pdf/EN/009/qw593....

I love my mechanical watches but I bought them because they look cool not for their time keeping ability.