As a general rule, I tend to stay away from items or devices geared towards the paranormal investigator, pretty much anything that is labeled as a ghost hunting device, or something as seen on whatever ghost show is the more popular, or or or.
One thing that I've seen a lot of paranormal groups use is an EMF detector called the K2 (or the K-II), a cheap EMF detector that originally sold for $30, but somehow went up to the $60 range after it started showing up on Ghost Hunters. And it seems that a lot of groups use this device because, well, a lot of groups use this device. It even got to the point where I was considering purchasing one because "everyone was doing it".
Believe it or not, I do try to research a product before I purchase it, paying close attention to the reviews and the specifications. And lately, I've been looking into the K2, and have come away scratching my head as to why groups are using this. The K2 is a faulty device, one that will register if jostled, lightly bumped, or moved to quickly; additionally, the older models would tend to give false positives because the on button was a pressure sensitive button.
With more and more information coming out about how to create false readings with a K2, groups are now saying that it is still a good device, you just have to use it in conjecture with another meter, that if the K2 goes off and the other meter doesn't register anything, then it was a false reading. Some online stores have even started to sell the K2 along with a different digital meter because of this.
Really? If you are using a device to test the accuracy of an other, then why are you using it in the first place? Wouldn't it stand to reason that you should use the testing device instead of the faulty one?
When I began buying things, I bought a cheap (I cannot stress enough the word "cheap") EMF detector. I knew it was cheap when I bought it, I was just curious as to how effective it would be. It went off like crazy when pointed at an energy source like a toaster or a lamp, but it wouldn't register an open cell phone. It also went off if it was tapped, moved, bumped, and so on. There are better things out there, and I did get better for about the same price, too (and it can detect an open cell phone).
All I am trying to say is, research something before you buy it. Just because everyone is using it does not mean it works, it just means people have fallen for the hype. They bought into the advertising. And if you're buying the K2 because it lights up, making it easier to communicate with a spiritual entity? Go with candles. They're cheaper, they are more inline with traditional rituals or practices, and you don't need to buy a different candle to see if the first one is working or not.