Walmart offers two Blaupunkt 4-Way Waterproof Marine / Car Speakers in White for $21.50. Opt for in-store pickup to dodge the $5.99 shipping charge. That's the lowest price we could find by about $12. (For further comparison, it's the cheapest pair of 6.5" marine speakers we could find.) Each speaker features 80-Watt RMS, frequency response of 80Hz to 20kHz, and mylar dome tweeter.