I've always been fond of silver. Most silver pens are disproportionately expensive.
Montblanc do some pens with sterling silver caps that are particularly nice. Beaten up vintage ones are things of beauty.
I'd given up on the idea of one of those, but then came across the Parker 75...
The 75 has a full sterling silver barrel, a 14k gold nib, and a nifty mechanism for twisting the nib around, so that the triangular section is always exactly angled to your writing position.
They are relatively cheap (for a good vintage pen), and also relatively easy to get hold of. Anyone with a love for silver should really give them a look.