Plus Size Dress Problems

I am having a 1958 theme wedding in April 2006. I am wanting a wedding dress similar to styles that were popular in 1958.
My problem is finding vintage clothing in my size - I`m a size 26w (working towards being a 24w by the wedding date, possibly a 22w).
My brides maids are also plus sizes, we are having the brides maids weare poodle skirts and we are hoping to find some of the frilly lacy under slips to go with.
Does anyone know of places where i can purchase vintage clothing styles in the larger sizes?
If I end up needing to have a dress made, how do I go about finding a dress maker? and what do they usually run price wise? How long does a dress usually take to make?