As said the rotors can be measured as to whether they need to go or could be resurfaced. They must be a certain thickness even after the machining or frequently warp and you won't be happy.
I'm shocked at the junk mail I see that claims just pad replacement which is really just bait to get you there and tell you they really can't do just that and if they are it's irresponsible auto service!
Quality new would be my suggestion. Rotors don't come with lot's of extra metal to machine off anymore. They days of doing that for three or more brake jobs are over. Cars don't weigh 10 tons either!
T
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Tom Greenleaf - MetroWest, Boston