JBL offers its JBL Arena 125C Center Channel Loudspeaker in White for $79.95 with free shipping. That's $50 under our mention from last month and the lowest price we've seen. (It's the best deal now by $20, although most stores charge $180 or more.) It features 90Hz to 40kHz frequency response, 89dB sensitivity, and 8-ohms impedance.
You very likely are putting your laptop battery into an early grave.