What's the best gaming headset for office use?
Preferably comfortable to use,high quality and low cost?.
Does it have to have a built in mic? If it does then your choices would be quite limited.
Otherwise, the ATH -AD700 is very commonly recommended because of it's huge soundstage. The Fischer Audio FA011 is supposed to be very good for gaming/movies too. It has a lot more bass quantity than the AD700 which is very bass light so it'll probably be nicer for stuff like explosions. Both are extremely comfortable headphones.
I'll add to what sari0n said, and say it is probably best to get a seperate microphone. Most headsets skimp badly on quality, so make your own!
So, perhaps get a standalone mic, and a good headphone recommended here. Get two little velcro strips, put one on the mic and one on the side of the headphone. Then stick it on and hook them up accordingly.
If not you could always have a mic that sits on the table infront of you and a good headphone.
*EDIT: I recommend that you get a closed headphone, so it is easier to stick the mic to the headphone cup. Also, I think closed headphones are the norm for gaming. If I remember.