René Herse Porteur bike? value? help?

As with any vintage bike it depends on the condition and how many of the bits are original. Herse bikes are generally rare and very valuable to the right collects, but a few missing parts will have a huge impact on the value. You might start by sending an email to Jan Heine to see if they can give you better advice about the bike and any restoration work it might need. Good Luck!