I've always heard that the Century Optics fisheyes are good. They usually make 3 different kinds for a particular setup. Super, Ultra, and Extreme (going from least to most distortion). One of the most popular ones is the Ultra (well at least in the Action Sports field). For some reason that one is still omitted from the HVX lineup, I believe. The Extreme is new (or at least I've never heard of it before doing some price checks a month or so back). These fisheyes range from roughly $500 to $2000. The more distortion, the higher the price.