Amazon offers its Prime members this Hipo By Ivation Multi-Function Bicycle Speaker with Travel Case for $34.99. Coupon code "15DISCNT" cuts it to $19.99. With free shipping, that's $50 off list and the lowest total price we could find. (Non-members get free shipping with orders over $35; otherwise shipping adds $5.70.) It features an amplifier, 3.5mm auxiliary jack, and USB reader. It also includes a 1000mAh rechargeable li-ion battery for up to 15 hours of continuous play.