Pacific Supply Co is the only hardware store in Capitol Hill. I went in there the other day to find a locking door knob for my apartment door (which they did have).
Keep in mind that this store is an apartment and building supply store so the selection of goods is not that great. Its perfect if you break something in your apartment and need a replacement (great for the glass globes surrounding your outdoor lights) but you will not find lumber or a wide range of tile.
Basically if you can find it in your apartment you can find it at Pacific Supply Co.