If you looking for full-size, Jaycar (rebranded FA-003) for 70$ imho is best bang for the bug. For me it beats S500 in everything except bass quantity, but not by far. It is the best sounding headphone I have ever heard (not heard anything higher than Senn 598 though).
Edit Price for UK is 27£ + 5£ shipping - unbeatable
Edited by Jakkal - 4/19/13 at 3:00pm