Under $20 and has great bass, it's what I use.
FYI, if you EVER see a non-audiophile utter these three words it should be an instant red flag, I'm not trying to be rude or anything but good bass is VERY rare in headphones, especially cheap headphones, and even a lot of audiophiles don't know what truly good bass is
Oh, and, I just remembered another headphone, the TEAC CT-H02 (AKA Tascam TH-02):
[link]EDIT: holy stuff the Tascam version is even cheaper; thanks B&H:
[link]This thing, holy stuff. This little beast measures better than
any of the other currently-produced studio monitors at a RIDICULOUSLY low price point (<$30).
Strictly looking at performance, the Superlux's should be better overall for your application (gaming), as they probably have the better soundstage/seperation/placement of the two, but the CT-H02 would be a good option if you need to have isolation and/or listening privacy. It'd also be a good portable headphone on a budget. It even has modding potential if you're into tinkering.