For under $50, I'd go with koss ksc-35's($30) from koss. They're about as good as you're going to get for under 50$.
If you want to spend a little more, the Grado sr-60 or the Sennheiser hd-497, or Sony mdr cd-580 would work for open. Or the Sony mdr V6 or Sennheiser hd-280 for closed.
If you want to spend a little more, the Grado sr-60 or the Sennheiser hd-497, or Sony mdr cd-580 would work for open. Or the Sony mdr V6 or Sennheiser hd-280 for closed.