Pinnacle Deals via Amazon offers the refurbished Sennheiser HD-203 Over-Ear Headphones for $10.99 with free shipping. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.58.) That's $26 under the lowest total in-stock price we could find for a new unit, although we saw a refurb for a buck less last April. These headphones feature an 18Hz to 18kHz frequency response and are intended to reduce ambient noise.

Of note: It's unclear whether this item includes a warranty.