twister6 just posted a review of the HD-668 B headphones over on Head-Fi. From the review they sound pretty good and with a $37 price tag their price performance in outstanding.
Pros: impressive price/performance ratio, giant killer sound performance, removable cable, replaceable earpads.
Cons: isolation and sound leakage due to semi-open design, not a typical removable cable.
Review of HD-668 B
Mark2410 has a comprehensive review of the HD668 headphones on Head-Fi. With a bit of equalization to tone down the highs these are bad headphones. Especially with a price tag of under $50.
ThatBeatsguy has posted a review of the HD 381F IEM on Head-Fi. Its tonality and look is similar to the DUNU Titan 1. The primary difference is that the HD 381F is on $13. Not bad.
Pros: Excellent sound quality in an unassuming package.
Cons: Looks and feels cheap. Treble is a little bit on the laid-back side.
Review of the HD 381F