Infrared Thermometer
If you intend to take temperature readings at an investigation, consider a digital thermometer. Not only do they keep a memory of the highest and lowest monitored temperatures, most come equipped with alarms and take measurements several times a minute. The alarm feature is especially helpful in letting you know when sudden and drastic changes occur and allows you the convenience to focus your attention elsewhere. A more expensive option for instant temperature measurements are the new infrared laser scanners. A point-and-shoot device that detects temperature differences using infrared technology.
Torches
There is no doubt that your investigations will sometimes include dark foreboding places. Cemeteries, old buildings (without electricity), battlefields and the like will all require a portable light source.
Compass
If you cannot afford an EMF meter initially, you can use a compass to detect magnetic fields. A ghostly anomaly will usually tilt the needle at least 30 degrees off Magnetic North. Again, be sure to rule out a possible electrical source.
Infra Red Motion Sensor
Try leaving an Infra Red Motion Sensor in an area where there is suspected activity. This will quickly alert you to any movement detected in that area allowing you to get there fast to investigate. Be sure that everyone attanding the investigation knows the location of the sensor to prevent accidental activation.
Trigger Objects
Try using trigger objects in areas where there has been reports of things being moved. Lay down a piece of paper, select an object ( ornament, wooden cross etc), lay the object on the piece of paper and accurately draw round it with a pen. Leave the area alone for a while and then return to see if the object has moved. Be sure to alert everyone on the investigation to the whereabouts of any trigger objects to avoid accidental movement of the object. You can also use an Infra Red Motion Sensor in conjustion with the trigger object, this will alert you to any movement. Try taking photographs of the object before you leave, and then again when you return.