I'd agree on the HD 580 point.
To the original post:
Koss R/80. $33. Very good overall. Balanced, nothing sticks out, comfortable, well put together, enjoyable to listen to even if you've heard much more expensive cans. The cord is a bit weird, and the headband mechanism is imperfect, but for $30, what do you want? They sound good.
Over $50, Sony MDR-F1, ~$250-$300 (when last in production). Unrivaled. I've yet to hear a dynamic headphone in the price range that can compete in terms of soundstage, tonality, comfort, detail, etc - they best the MDR-SA5000 (which are better than a whole lot of things and list at $700) and K701 (which list out at $550) easily, and deserve a spot at the table with 'stats and other exotics (generally headphones in or around their price range screw up something somewhere or other that lets the F1 outshine them, they are as close to "stat like" as I have heard in a dynamic can, and I've yet to find something truly more comfortable anywhere at any price for any reason (yes even compared to the Bose headphones)). Supposedly back in the early 2000s when Sony killed them for the first time they were around $150 for a while too.