Whew. That was a mouthful.
So I think I may of found the headset I am looking for. The Ear Force Z2 by Turtle Beach seems to have everything I need: compatability with both the PC and 360; the lack of a static sound during silence (which is something nearly every Turtle Beach headset has, sadly); a price tag of $50 on Newegg. Yep, can't go wrong!
... But just incase, I'll be buying the extended 1-year warranty, too. :P
The only thing that bothers me is that in order to get it to work with the 360 I'll have to buy an optional cable from Turtle Beach's website. It might only be $5, but the shipping is $10... damn them. Looks like I'll be calling up some Best Buys and seeing if I can get it in-store.