Dell Home offers the VisionTek SoundTube Pro Speaker for $54.99 with free shipping. That's the lowest price we could find by $13 for just the speaker. (We saw it bundled with headphones for $90 in April.) It features a 180Hz to 20kHz frequency response, microphone, IPX4 water resistance, and a rechargeable Li-ion battery with up to eight hours of playback per charge. Deal ends July 31.