Planning on building a new system in a week or so. Looking for a good gaming mouse and keyboard. Around $50-$60 apiece. However, if I could save money, it would be awesome. =P Here is some things I am considering.
Personal preference. Outside of a $10 mouse/keyboard combo, as long as you like the shape, design, and feel of the mouse, its totally personal preference. I do recommend a USB connection over wireless though, as batteries are an upkeep, and can cause accuracy problems when the battery is dying.