Amazon offers the Panasonic ErgoFit In-Ear Headphones
in Violet, model no. RP-HJE120-V, for $6.19
. (Several other colors are available starting at a few cents more. ) Plus, Prime members bag free shipping
. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.01.) That's the lowest total price we could find by a buck. They feature a frequency range of 20Hz to 20kHz, and include three sizes of earpads.