Does anyone know if it's illegal to sell a used (genuine) designer bag on Craigslist or Ebay? I want to sell an old Prada bag that I no longer use, but I want to first make sure that what I'm doing is legal.

Is there anything I need to do or consider when doing this? Also, if anyone has done this before what percentage mark down would you give for a used bag that is slightly worn and a couple years old?