Arch is a general arts supply store with a variety of drawing supplies: pens, notebooks, sketchbooks, pencils. Next to the counter there is a small case with a few fountain and rollerball pens. Most of the inks they carry are not fountain-pen inks, but they do have a couple brands of fountain-pen-friendly ink in stock.
Flax Art & Design is San Francisco's largest art supply store. Their dedicated pen counter is immediately to the right when entering the front door. In addition to fountain pens and rollerballs, glass pens and a variety of penholders can be found at this counter. Once a year, Flax holds a pen fair, and brings in representatives from major fine penmakers and distributors.