Amozing via Amazon offers Prime members the Sony XB Extra Bass On-Ear Headphones in Blue, model no. MDR-XB400/BLU, for $31.99 with free shipping. (Non-members can spend $35 to bag free shipping; otherwise, it adds $6.59.) That's the lowest total price we could find by $5. They feature 30mm drivers and 5Hz to 22kHz frequency response.
Update: The price has increased to $32.95.