I always have problems quoting prices as well. its much easier on a job type you have done already but when a new/different job comes in I have trouble pricing. I am pretty good at material estimations but the time part gets me. Sometimes I blow through a project and sometimes it takes a couple tries before I am satisfied(we're all picky!).
location has a lot to do with it as well, I know I couldn't charge half what I do here in the big city as I could in my small hometown for the same job. maybe shop some local upholsterers and see what they would charge to "duplicate" one of your door panels.
edited, forgot to give you props on the work. tremendous job man, looks great, I would be proud.