Like I said above, your brakes are covered under warranty for 3 years or 36,000 miles. Unless you have been beating on your car they should have lasted longer. If the rotors are so low that they cannot be machined, you would have heard a grinding noise when braking. And, even if they are unable to be machined, they should be replaced under warranty.
Why spend the money now if you don't have to? If you are that hard on brakes, why spend money on them for them to go again in another 20,000 miles? I don't think that going aftermarket will make a difference. In fact, you will probably have more problems with noises and dust, etc.