for gods sake, do yourself a favor and buy Turtle Beaches already!
http://www.turtlebeach.com/products/xbox-gaming-headsets/ear-force-x11.aspx
No offense, but Turtle beaches are physically built like a piece of shit. I will admit the Turtle Beach DLC is a good buy for 30 bucks because at that price, there's nothing comparable to them at that price point that works for the xbox360. However, I don't think you'll be using it on anything else like an mp3.
Senheisers do have gaming headsets that have mics in them. But I hear mixed reviews about those mics usually that it picks up weird noises.
I know that the Steel series Neckband is good. However, for some people it's too small for their ears and thus is a little uncomfortable for long periods. My brother uses Tritons which aren't half bad, but those roll about 55 quid here ($110). Astros are arguably superior and are probably around 80+quid.
Razer gaming headset I'd recommend against. Look up the specs, there's a battery thing (somewhat heavy) to power it and stuff. Sort of lame to have an anchor on your headset.
In all seriousness, If you're really strapped on cash, look either second hand, or Sony. I think Sony will give you the best bang for your buck in the mid/low range. Preferably I'd suggest sennheisers. I regret nothing about that purchase. However, I will say that the Tritons give a nicer low range which is more preferable for gaming. The artificial surround sound it gives is pretty cool too.
I think Grados or Audio technica are more for listening to music than gaming though. Sure you can plug them into your home theatre system to do the same thing, but really, it seems silly to do so.
The steel series neck band has the best mic I've ever used. It's insulated so it doesn't pick up crap noise, it's retractable so you can put it away and it's flexible so you can't technically break it in any conventional manner. However, someone stepped on them, so they're broken on one side. I have no idea what to do with it now.
