I swear by my 6-year-old Logitech MX518...there have been nicer looking and fancier mice out there, but none can beat it in my opinion, and it doesn't cost an arm and a leg either. Goes up to 1600dpi (which I almost never use) and DPI is switchable with two buttons on the top and bottom of the mousewheel and configured in the Logi mouse app (but you don't need the app to use the mouse)...really, what more do you need?
'Who am I?...I am the right hand of vengeance and the boot that is going to kick your sorry ass all the way back to Earth, sweetheart! I am death incarnate, and the last living thing that you are EVER going to see. GOD sent me.'