Metageek drops down a few gigahertz with the Wi-Spy 900x: The new spectrum analyzer from Metageek, in a USB dongle form factor as with previous offerings, extracts data from the 900 MHz band, an unlicensed band used for cordless phones, baby monitors, RFID tags, ZigBee, and other mishegas. The price is $199. While WLAN use 2.4 and 5 GHz, there are still plenty of purposes for 900 MHz devices, which take advantage of the better propagation available at this frequency range.