although I'd never use these myself (I hate gemini products) here's some that are at a decent price
http://topdjgear.com/gemini-em-100.html
Most of the more expensive (Pioneer, Sony etc) dj headphones have a swivel and a latch that you can release one of the cups. I love the pioneer headphones and use em when I spin.
http://topdjgear.com/pionhdprofhe.html
a bit pricey and probably way more than you need but I gotta brag about em