I think I got it for a bit under $20.
It shows the strength of the signal, with the number of LEDs that illuminate.
What it doesn't show you is if the signal is secured, meaning you will still have to fire up the laptop to check that out.
Also, it doesn't show you what the direction is that the signal is coming from. You may think that is a "no brainer" just by walking around a bit, to see what corner of a room the signal is stronger, but not so. Just because you have a stronger signal in one corner of a room does not indicate that the direction must be from 'there' because perhaps the general room shielding and other influences are affecting the signal in the actual closest corner.
I think there are some newer technologies for WiFi finders that may help through the above stated issues, but I am not made of money. I can use my laptop to see if a signal, its name, and if security is enabled.