I've got a dual metal-mesh panasonic shaver with a slotted deal that goes back and forth between them and it has a pop out beard/mustache trimmer...
Works great, even when I've got about 1/4" worth of growth going on

.
It was about 65$, but you don't have to replace screens but once a year, and the internal cutting head every other year.
Sam
EDIT: it looks similar to this one:
http://mywebpages.comcast.net/steelbeard1/gallery.htm