For powerful bass in that price range you will want a closed headphone, as open headphones dont deliver enough punch to be powerful. They may be accurate, but it will lack the volume you want.
You really have two good options right now, AudioTechnica ATH-M50s, or Ultrasone HFI-780s. Both are low impedance, 38 ohm and 35 ohm respecitvley, so they can be used on the go, and both are closed.
The ATH M50s bass should be more "in your face", as the speakers are very close to your ear, as opposed to the HFI 780s, who have a wider soundstage.
However, you would be doing a disservice to yourself to pick up a nice pair of cans like these without a dedicated sound card, so look out for a used Xonar DX, or if you cant find one, even a Xonar DG. These headphones wont really shine unless paired with a quality source, and put through quality hardware, before they reach the headphones themselves.
EDIT: They also both look really good