Video camera (optional tripod) - This can be used for video taping in lighted or day light conditions only, unless you have a camcorder that has a low lux setting (the ability to record in low light) or the new night vision type which can record in the dark. The camcorder with the night vision is great for this type of work, because many times you will be at a site in the dark. O.G.H.O. has bought a couple cam corders one is a regular camera and the other is a Sony Nightshot with a very good low lux setting I (and others) have recorded some interesting, orbs in motion with these cameras. These orbs seem to know when they are being tracked by the infrared beam, they seem to move out of the way or speed off when you film directley at them. These are a valuble tool for the experienced ghost hunter or the beginer alike, I just think they are a little pricy for the beginer.What We Use is pictured above, it is a Sony TRV16 with 0lux capabilities, we got it at Circuit City for around $300 and it has been the most interesting peice of equipment I use.
Tape recorder w/ external microphone and high grade tapes - You have to use a external microphone when recording EVPs (electronic Voice Phenomenon) the ones with internal mics are bad to use because the mic inside the unit will pick up the sounds of the running tape recorder motor. Any sound you hear on the tape could probally be the sound of the gears and you wouldn't be able to distinguish them from the EVP, so use the external mic, they are pretty inexpensive, I got mine for around 40 dollars. The type of tape that is most often recommended is high bias tapes or metal tapes.
(O.G.H.O.) doesn't believe alot of the voices many researchers collect are actual EVP, alot of these other evp's were recorded while organizations were holding large tours or events and some of them don't measure in the MHz range to be paranormal in nature.
EMF Detector - These meters read the electromagnetic fields in an area. It is a common belief that entities disrupt this field in such a way that you can tell when one is present by higher than normal readings with this meter. There are many types and price ranges. You need to be aware of the natural readings in an area or building before you assume that your reading a ghostly presence. Make sure that you know where power lines, electrical lines, major appliances and electronics are before you begin your readings with this useful and easy to use tool. You can try using a compass in place of this, the needle of the compass would move or shake when something was interfering with the electromagnetic field. O.G.H.O. believes that these are very important tools to help locate and even track an entity so much we had some malfunctions with ours and rescheduled most of our investigations until we could find a replacement. The ones we use are Dr. Gauss meters and we bought them for around 50 dollars a peice (just don't drop them they are fragile), and they are simple to use even for a beginer you just turn it on and use a sweeping motion around the room and if you get a reading of between 3-7 take some pictures and log it in your journal.What We Use is pictured above, it is a Dr. Gauss Meter and the only place I have found to buy them is on the internet. The price of these has came down ten to fifteen dollars since I bought my first, you can usually find them for $40-$50. These are very fragile and if you drop them (even from a short distance) they could and probally will break.
Passive IR Motion Detectors - these can be used to sense movements by often unseen forces or spirits. You can get battery operated ones for about 20 dollars and they are great for inside but I have seen them used successfully outdoors as well, just watch the placement. you don't want a tree branch setting it off.What We Use is pictured above, it is from RadioShack and one unit cost us around $35, they are extremely loud & this model even came with a remote to arm and disarm it.
Thermometer or InfraRed Thermal Scanner - You can use a digital thermometer that you can get for 25-50 dollars or spend a few hundred to get a point and shoot thermal scanner. All of these are good for detecting cold spots that are often found in haunted places. I recommend using the thermal scanner guns in indoor areas because they shoot out a beam that reads the temperature of whatever it hits. It's easier to keep track of areas indoors with this type. A regular digital or analog thermometer works better out side because it is detecting the air that is currently in, so if you hold it in a cold spot and them move away, you would get a temperature increase and that would give you a truer reading of the temperature difference.What We Use is pictured above, it is a model through RadioShack, it cost us around $100 not counting shipping and handeling.
Hand Held Radios - Or Walkie Talkies are very useful in a large outdoor area and a building with groups spread out in various rooms. They could be great in emergency situations or just to rotate groups. Be sure to be aware they could interfere with your EVP recording though.
What We Use is pictured above, they are Cobra 2-Way 14 channel radios.
Entity Chime - I saw this on another crews web site but thought it was a good idea. The idea behind these is that when a spirit moves it creates a trail of wind and these will help you track the movement of the spirit. You can get a detailed list and instructions for these here Tips and How To's