Actually, Steve with Ahooga picked up a '31 Std. Phaeton body from me a year or so ago with the intention of reproducing the center section, rear section, rear doors and the sills. This would allow someone to use the Roadster cowl & doors already being manufactured to assemble a 35B body. Alternatively, I have gathered most of the drawings, samples, patterns, dies, etc. of the wood and sheetmetal to reproduce the 180A body. Unfortunately, the only thing I have not gathered is time.
As to the difference between the Roadsters and a Phaeton body being reproduced is, I doubt you would ever see the price of the Phaeton body rivaling the price of the Roadsters simply because of tooling costs. Dave I don't know what your intentions were by asking this but FWIW, I know where there are both styles of '31 Phaeton bodies that can be purchased if you or someone is in the market for either of an original body.