I know the rear quarter panel is "part of the car" and not really a piece you can take off and swap out like most other body parts but are there any places that sell replacement panels? Or would I be better off finding one in a junkyard and doing what i can with that?

I'm talking about my '04, I did the best I could with the body filler and paint and it doesn't look bad but it could be better. I was thinking I could cut out the whole bad area and weld in a new piece but I'd need a donor...

Finding replacement rear quarter panel