I certainly wouldn't turn a warped rotor. If it warped before turning, you may have an even worse problem with it being thinner. Besides the price of rotors allows you to replace them without breaking the bank.
I would also go with Wagner brake parts, but my personal preference is with O'Reilly's. But that's mainly because there's one nearby and they're usually cheaper than Advance Auto Parts. I usually check Rock Auto also just to see if I can make it worth while with the shipping costs. They are usually much cheaper than locally, but the shipping charges usually kill any savings.