Surprisingly, my Genius GX Gila has help up surprisingly well. 12 buttons, left or right hand design (for most of the buttons anyway), lots of lighting options if you care about gimmicks like that . . . They go on sale all the time at NCIX around the price you are looking for. I would probably choose something else for it's regular price because there are probably better options at 100 bucks.
Personally I don't like a huge rack of thumb buttons so that rules out a huge pile of MMO/RTS designed mice that say they have lots of buttons, but it ens up being like a number pad just for your thumb.