I've been here long enough to know that some people think it's a crime to spend less than $200 on a piece of audio equipment. I've never heard anything remotely that expensive (except the Bose/Dr. Dre/Skullcandies on display at Best Buy...), so I remain blissfully unaware of what I'm missing...

Long story short: I'm going on a five-day bus trip. The bus is loaded with very loud high-schoolers. Are there any semi-portable headphones that would work decently under $50, and without an amp? I know I am completely inexperienced; the only real phones I've used are my brother's SR-60i and my...