Looks like a somewhat portable device (MODEL 243): http://www.radarengineers.com/rfitvi.htm Although it's probably going to cost you $5-10k USD.
Pretty easy to hook up a RTL-SDR ($10) to a cheap Android tablet loaded with SDR Touch for simple surveying.
Google is very weird sometimes.
Note: I have never watched "My Little Pony", collected anything related, visited any My Little Pony fan sites, read any My Little Pony fan fiction (not even accidentally, via crossovers from fandoms whose fiction I do read), or done anything else to show any interest whatsoever in My Little Pony. Google has a ton of information about me with regards to things I might actually buy, so why the heck did they pick My Little Pony? (Heck, I'm pretty sure they have figure out that I have a ham license...surely they have something more relevant for me than My Little Pony).
For hunting a strong signal, the traditional tool is antenna with a deep null such a loop antenna. The reason for this is because the null at a point can be very deep relative to the average response-- e.g. maybe a small directional antenna has 10dB difference between the front and the side, but a small antenna engineered to have a deep null can easily have 40+ dB of isolation between a null and the side. To search for a signal using a null you aim until the signal goes away and you go in that direction. :)
And it's easy to construct antennas with only two (or one) null.
For a directional antenna like a yagi you have various reflections hitting the antennas sidelobes, making it harder to read.
When the rabbit-ears TV in the same room was turned on and tuned to the right frequency, you could hear the leakage from the drive; it sounded like lower-frequency modem chatter. Not entirely sure what part of the drive was leaking that much RF, but I don't think it was intended to work that way.
Professional handheld spectrum analyzers are in the $3k-50k range from the likes of Keysight, Anritsu, etc.
It might seem like the poor man's approach, but plug a good Yagi antenna into that dongle and it becomes quite powerful.
Another approach seen on hackernews in the past had an omnidirectional antenna and used GPS tagging to make heatplots at different frequencies overlayed on a map. ref: http://www.tautology2.net/heatmap/ It uses the http://eartoearoak.com/software/rtlsdr-scanner software.