Amazon has the Sony MDR-V150 Monitor Series Headphones with Reversible Earcups for $13. Shipping is $6 or free with Prime or on orders of $25 or more.
Technical Details:
* Supra-Aural Design for excellent listening ability
* 30mm diameter driver units provide deep bass
* Fixed stereo miniplug for use with portable equipment; detachable phone plug for studio and home audio equipment
* Wide molded headband gives long-lasting comfort; oxygen-free copper connecting cord
* Reversible earcups for single-sided monitoring
Amazon.com: Sony MDR-V150 Monitor Series Headphones with Reversible Earcups: Electronics
Sony MDR-V150 Monitor Series Headphones with Reversible Earcups $13 (FSSS Eligible) 
