I would like to know where I can buy new or used car body parts for a Nissan Exciter model, year 2001. Preferably in Pattaya/Chonburi area.

I believe this vehicle was built by Thairung, the Thai car manufacturer. It was based on the old Frontera Navara D22 model. So depending on which parts you are after you could chase up Thairung or Nissan.

At the end of the Chonburi bypass there are several vehicle dismantlers who might help you with this too. There are also several body  shops dotted along Sukhumvit ...you can see the panels and trays stacked up in rows outside 

Production of the model I'm thinking of ceased around 2006??