Mine at work goes up to 5700. It has the ability to shift DPI at the click of a button on the mouse so it works well when head hunting and stuff.
Can have five settings at once. Currently I have: 350, 800, 1600 (most commonly used), 3200 (occassionally used), 4500 (for shiggles when anyone wants to use my laptop )
I got the Logitech G9x. Works well. Nice feel, balance and weight. Looks pretty. Has wing for thumb but not pinky which I like as well. $40 - not a bad buy. Work also gave me $20 for it so total cost to me was only $20