Wow. I appreciate all the suggestions for light fixtures. I probably should have mentioned that I have already exhausted most of the possibilities offered. I have looked at every lighting store in Portland, including Lowe's, Home Depot, Restoration, Rejuvenation, Globe, etc. I have seen many Mission and Arts and Crafts style lights.
I looked at every single web site you sent me and didn't find this exact light. What I especially liked about the one in the picture is that it does not have the typical ornamentation of this lighting style—no overlays, no leaded glass, no mica shade, but it does have nice substantial hardware, which appears to be copper, and the shade is plain glass. I liked the proportion of this one as well. It seems simple, but sometimes those are the hardest things to find.
I may have to settle for something else, in which case you all have given me some options. Thanks!