I've got the Nittos, and love 'em! They didn't negatively affect my gas mileage at all - actually, since I do a lot of highway miles, I think they helped. Had to trim just the barest sliver from my cladding (see my gallery for pics). They ride well (at 38 cold psi), and look mean as hell. I couldn't be happier.
However, I gotta say that $908 is NOT a good price at all. You can get the tires themselves online for $174 a piece. My local guy got them for me for a mounted-and-balanced price of $178 each.
Good luck!
Ron