Are all iPhone sync cables the same?

My cat destroyed the sync cable that came with my iPhone 4. I noticed that they don't sell them at BestBuy so I went on eBay and there are like a 100 different sellers selling iPhone sync cables. Are they just as good as the official Apple ones? Can these cheap ones damage my phone?

Thanks.

They are not expensive compared to taking a chance with a cheap cable that no one will stand behind in case of incident. Apple Dock Connector to USB Cable - Apple Store (U.S.)

Thanks for that link