Vintage Motors of Sarasota has one of the Martin and Walker 904's. It is beautiful. Here's the link.
http://www.vintagemotorssarasota.com.../64porsche.htm
They will not budge on price. I was turned away at a reasonable offer. I think they really like having it.
There are a pair for sale in Germany that were built by an ex factory mechanic. one complete for about $80k and the other without engine for around $60k. They disappeared from my links about 4 months ago but I could find the contact info if you really want. He was making no more.
For me it's the Carrera 6 like this one I saw at a rally in France. It makes me have crazy thoughts.