Hi, author here -- I agree, the BladeRF is overkill for this kind of application. But, we were done with what we needed it for and it was just sitting around our lab so we decided to use it. I did use an RTL-SDR to poke around in the lower half of UHF, though.

Also check out the HackRF One! You can look at a much wider spectrum, as well as broadcast. The thing itself is 300$, and completely open. (https://www.sparkfun.com/products/13001)

For those of you, like me, outside the US, be prepared for some interesting questions on ordering a HackRFOne (or I suspect the BladeRF or USRP or probably any other transmit-capable SDR):

Your recent SparkFun order contains 2x WRL-00705, 1x WRL-13001. This item is export controlled by the United States government. By law, we are required to gather the following information from you as the importer:

1) Do you intend to sell or send this item to anyone in any of the following countries: Cuba, Iran, North Korea, Sudan, or Syria?

2) Will this be used in any military applications?

3) Will you be the ultimate end user of this item? If no, please go to 3.a.

3.a) If you are not the end user, who will this item be sold or transferred to? Please include full name, physical address, end use and confirmation that they will not sell or transfer this item to any party in Cuba, Iran, North Korea, Sudan or Syria.

4) What is the end use of this item?

5) Where is the location where the item will be used?

Response to all five questions is necessary before we are able to ship your order.

(I hate to consider which "lists" I'm now on...)

Quite a lot of things seem to be export-controlled, for example this microcontroller dev board is: https://www.sparkfun.com/products/12646

To be honest, I'm not at all surprised - considering you can use it to do stuff like this: https://media.defcon.org/DEF%20CON%2023/DEF%20CON%2023%20pre...

(But then, you can use a hammer to bash someone's brains in, and we don't export control them...)

Much narrower bandwidth though, and limited to below ~1700KHz - you can't snoop on WiFi/Bluetooth/upper-end-GSM-bands without futzing around with downconverters.