Logitech S120 2.0 Multimedia Speakers for $6.42.  Shipping is $0.97 for a total of $7.39 shipped.  Here is a screenshot for reference.  Note it comes in OEM packaging, which means no pretty retail box and marketing materials but is otherwise identical.  It features 2.3 watts of power, frequency response range of 50Hz to 20KHz, and more.