I have a brass Kaweco Liliput, and it is an EDC workhorse for the past 2+ years. It's been through the wash a half dozen times now—I sometimes forget that it's clipped in my trouser pocket. The nibs are easily replaceable if you drop or damage it (or just decide you like a finer or bolder line). It takes international short cartridges (but doesn't have enough space for a converter). I use Mont Blanc Permanent Blue cartridges in it.

In the 100+ USD range, I can't say enough good things about the Lamy 2000.