This entirely depends on your preference of style when it comes to wearing a headset. For me, I use the Tritton Stereo Gaming headset that is wired. Provides decent audio and I can hear what the hell people are saying, and it's 50 bucks. Just about every in-game audio engine will lower the game audio when people are talking.
You can go cheaper and get the single headphone with the mic for roughly $20-$30 but hearing people talk while the action is going on is going to be a problem. One of the reason why I can't stand the xbox 360 headset.
Then there's the wireless ear piece style. I've had success using the Sony ($30) and Jabba ($20) bluetooth ear pieces with decent voice, but when there's a lot of action you might not hear what people are saying.
For wireless headsets, the Sony one is very good at a decent price of $80 if you like that style.
Which ever one you are looking at, please make sure you check to see if theres a mic mute button/switch or not. With no switch, you mic is always on so remember that, lol.