I am setting up an auction site, and I am trying to wrap my head around setting up shipping. When I initially set up the shipping it is asking for the place of origin zip code. (no problem). But if my vendors are in a different state, their point of origin will be different. What plugin would you recommend to allow me to assign their own postal zone zip, so their shipping charge is being based on their postal origin. Can this be set up in a shipping class? How to accomplish this task?