Door weatherstripping

I saw the post by scarletlizard about putting in the new weather stripping. I was wondering where you're supposed to get the replacement? (junk yards?).The car that I'm going to be buying is missing hugh chunks and will need to be replaced.Also can you buy the moulding that goes around the wheel flares as well? some idiot painted the ones on this car silver and I have a feeling it might be caulk Thanks