Groupon offers the Monster Tower of Music 2 Portable Wireless Bluetooth Speaker for $99.99 with free shipping. That's the lowest price we could find by $24. This dust- and water-resistant speaker connects with up to seven other compatible speakers via EZ-Play and also functions as a portable battery pack. Features include a 20-watt output, built-in microphone, USB charging port, 3.5mm auxiliary input, and rechargeable 2,200mAh Li-ion battery with up to eight hours of music per charge.