Before you give your money away..
Because there is no official certification available for paranormal investigation, just about anybody can call himself an investigator. I'm sure plenty are honest in what they do, but there are scammers who take advantage of the opportunity to walk into someone's home and even ask the home owner to leave while they "investigate" the house. Possibly, a burglar has been welcomed into the home and given full opportunity to steal, snoop, or anything else besides looking for ghosts.
Anyone can print up an official-looking certificate and claim to be a professional. There are even online "colleges" that will gladly take your money and offer a paranormal certification course, even though it's just a piece of paper with nothing backing it up. No regulation, just a stranger coming into the house. Also, anyone can become an "ordained minister" online for a small fee.
I personally know of an elderly person who has been scammed and the financial loss has been gigantic. It makes me cry when I think about it.
Another horrible thing is that some of these "investigators" will trespass illegally in graveyards after hours, abandoned buildings, and other private property for which they did not obtain permission. The saddest thing I ever saw was a picture of an "investigator" actually standing inside an open grave (don't know why it was left open but it apparently was) and holding her meters or whatever she was using. I think that is so wrong.
I imagine most paranormal enthusiasts are honest, and become involved because of a genuine interest and passion for the field. But one still has to be cautious.