I would think salvage yards/recycling yards would be the best bet for factory seats. I haven't seen a aftermarket seatcover yet that didn't have wrinkles somewhere after being installed. That would be the crap outta me....
Even the seats they had recovered for the 300 V that overhaulin did at SEMA had wrinkles in them. Also the Dragon Wagan on Gearz used Katskins and they had wrinkles too. Even the factory seat covers do it, i had a 2011 Camora 2 SS that had to have the Driver seat cover replaced nder warranty, it had wrinkles after they replaced it, very irritating.
Hope you find a set.