The best source of bonsai pots that I know is Bonsai by the Monastery -
www.bonsaimonk.com . Unfortunately, they don't have all their pots on their online store, and a trip to them is the best bet. They are just outside Atlanta, GA. Other than that, I'd try a local bonsai show that had vendors coming. The Bonsai Societies of Florida seem to be an active group and might be able to help you out with some more local sources.
As for the height - I do believe that Treebeard is correct, its the measurement from the lowest point to the highest point. I'm not at home, or I'd look up my notes from a shohin lecture I attended last summer at the ABS seminar. I think they mentioned it there.
-Centaura