a couple years ago i did a brake job on my daughter's 2016 chevy trax. the rotors were in great shape, so i kept them for the next brake job....she traded off the car.
so, i have a pair of rear rotors (they are different from the fronts) that measure 13mm thick, minimum is 10mm, so there is lots of wear left. there is surface rust that can be sanded off or just run them and the rust will go away.
ebay wants $53 n change. i want $20. your choice.