Best entry-level portable, closed headphones?

There's no audiophile forum, so I figured I'd just post my question here.

It's high time for me to get new headphones, and I want to make the right purchase.

I tend to use my headphones the most on public transportation and on airplanes, so they need to be portable (no super-long cords) and closed. I hate charging shit so I don't want any noise-canceling cans. I want something not too expensive: not much more than $50 unless the difference in quality is going to be extremely noticeable.

What do you recommend? I was about to go with the Koss Porta Pro as per the holiday gift guide, but they don't appear to be closed.