So I'm going a different direction with my door panels (adding a second set of 6.5 component speakers) and I could use a second set of door panels. Where could one go to find a set, other than through a dealer?

if i were you, i'd just get the speakers and speaker grills to go with them. then mount the speakers and slice/connect the wires. then figure out where the grill has to be in order for it to line up, then cut the door panel and install the grills with screws or glue. the plastic is really soft, so you can just use a dremel tool to cut it.

That is what I did for the pair i have in there right now. I am going with 2 pairs of speakers in each door. I'm going to be fiberglassing the door panel to accomodate, i just need a second door panel for parts :)