Newegg offers the Arctic Cooling Portable Bluetooth Speaker in White or Lime, model no. S113BT, for $14.99 with free shipping. (Amazon offers it to Prime members in Pink for the same price, however stock is limited.) That's $4 under our October mention and the lowest total price we've seen. (It's a current in-stock low by $28.) It features a frequency response of 30Hz to 20kHz, 8-hour battery life, Bluetooth 4.0, and microphone.