B&H Photo Video offers the Harman Kardon Omni 50+ Wireless Bluetooth HD Outdoor Speaker for $289.95 with free shipping. That's the lowest price we could find by $210. Features include:

24-bit / 192 kHz HD audio streaming

dual 3.5" woofers and dual 0.7" tweeters

50Hz to 20kHz frequency response

IPX5-rated splash-proof design

up to 5-hour play time.

WiFi and Bluetooth connectivity