CowBoom's Deal of the Day today are the Audio-Technica ATH-AD300 open air headphones.
These are good headphones for the money and are especially popular with gamers due to the great spatials (soundstage) and price. $30 is the cheapest I think I've ever seen these headphones.
If you have an extra $40 to blow, I'd definitely snoop around for a $79.99 sale on the ATH-AD300's big brother, the ATH-AD700 (currently my prime headphones for music, and I'm an audio junkie)...but for $30, you're not going to find better gaming headphones.
Link to deal @ Cowboom