4 x AA Battery Holder with On/Off Switch : ID 830 : $2.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Amazon.com: E-outstanding AAA Battery Case 3PCS 4 x 1.5V AAA Battery Case Holder,4 Slots x 1.5V AAA Battery Spring Clip Storage Box with ON/Off Switch and Wire Leads : Electronics