Battery died on my less-than-fancy watch (pretty, though). Cost of battery replacement is a significant percentage of the cost of the watch, so I figured it'd be better to just do it myself.

The battery you want is a type 371 (amazon, ebay).

You may also need a watch repair kit. These can be found on amazon or ebay.

The tools from the kit you need are (after the jump):

A watch repair wrench (amazon, ebay).

A band link tool to remove the links to make it easier to work on the back of the watch (amazon, ebay).

A precision screwdriver set (amazon, ebay).

And finally, tweezers (preferably electronics or jewelry tweezers), from amazon or ebay.