newegg offers this OrigAudio Rock-IT 3.0 Portable Vibration Speaker
, model no. ROK3-W, for $19.99. Coupon code "WHIORX24" cuts it to $13.99
. With free shipping
, that's the lowest total price we could find by $5. This rechargeable device works with any audio device that has a standard headphone jack; it purports to convert music into vibrations that transform any object into a speaker.