I usually just buy new ones, and haven't had problems with the "cheap Chinese" rotors any more than the better "made in mexico" ones.
The older Taurus rotors were very prone to warping. It is IMPERATIVE that you torque them in three increm3ents to whatever the FSM says, in a star pattern. Overtorquing or going up to t torque limiter using an air gun one lug at a time is a sure way to have tyhe rotors warp. I also used Performance Friction carbon metallic pads as they worked better and lasted longer.

I don't think a warped rotor can be saved but maybe I'm superstitious.
Anyway, where I live, the rotors are automatically turned to the minimum thickness, every time. Even if it takes only a light cut they still get cut to the max. That's so the brake shop guys can sell you a rotor next time. I would rather buy a new one than have some jerk work on my stuff knowing far less than I do about the subject, other than he messes up thousands of rotors a year.

R.

PS: The real way to surface a rotor would be to grind it, but that's hard to find.