I bought a no name Japanese WP camera off Ebay. it's a great camera and very light. I bought holders from Chamonix (not cheap but excellent)
I had Richard Ritter make me a back to fit the holders and the rest is history. It's my favorite camera due to the weight/size ratio.
my advice; start with the largest size you can go for it will save you money in the end and you will make great contact prints from this size.