Check out the sticky "Where to buy parts" in the Tech section. Lots of links to different sources for body parts.
My personal favorites are Peter Debella, Walcks, Harry Sheets @ Midwest Willys, Herm the Overdrive Guy and your local craigslist. Willys rallys are a GREAT place to find good parts. Like others have said in the past, buy US made parts (used, reproduction, or NOS) whenever possible. Oversea parts are hit and miss on fit, finish and quality...
Good Luck!