The Razer Abyssus is an interesting attempt at making a budget gaming mouse with an ambidextrous design. Sensor wise the mouse is very well equipped and the 3500 DPI infrared sensor performs flawlessly on most of the gaming surfaces around except for the ancient SteelSeries QcK according to some users online. And the 3rd generation optical infrared sensor is not quite on par in terms of performance compared to the very latest laser sensors on the market, however, the sensor in the Abyssus does not use prediction which means you do not lose definition in some circumstances. This particular trait is extremely important in FPS games where you need absolute precision. This mouse is available directly through Razer for $49, but I spotted it on Amazon for only $44.99 incl. shipping inside the US. If you can live with having only three buttons at your disposal the Abyssus is definitely a mouse to go for, performance wise this is definitely on par with the more expensive CoolerMaster Sentinel Advance gaming mouse.
So the mouse is not quite a steal but generally good value for money if you do not mind the size and the number of buttons.