I want to put headlights in a body. I want to power them with an individual battery pack though. Is there any light sets that use a battery pack? I need 2 front 2 rear if possible

most light sets I've seen are designed to be plugged into the Rx but I don't see any reason why you can't use a cell holder with a servo wire plug to power them too.

Check out NitroRCX, Integy and HobbyKing for sets like these:
SK LED Light Control for RC Cars MAD-NH3137-LED-Light