Digital Camera

Penetrating Meter / w slide hammer

thermo hygrometer

non-invasive meter

boroscope

thermal imaging camera

IMO it is better to have a different meter for each application rather than and all-in-one meter. Mainly because of penetration depth and accuracy of the non-invasive not to mention it is annoying using leads instead of just "jabbing" with the meter.

My personal preferences for the equipment above are:

Penetrating- Delmhorst BD-10 w slide hammer (great assortment of pins, easy to use, analog readout shows well in picture documentation)

Non-invasive - Tramex Moisture Encounter Plus (great penetration, easy to use, analog readout shows well in picture documentation)

Thermo hygrometer- Extech RH490 w/ GPP (quick response time allows for less time spent monitoring and documenting)

Boroscope- Rigid seasnake

Thermal imaging camera- Nice to have but it is in no way a replacement for the above detection equipment. A properly trained tech with the meters above is far more capable of detecting moisture, determining its source, and determining if a structure is dry than a tech relying on thermal imaging. It is however a nice addition to the arsenal provided you are properly trained in when and how to use it.  If purchasing a IR camera look for one with "fusion" which surrounds what you are looking at with a visible light image. Makes life much easier.....

As far as mold detection your eyes, your mouth, your nose, and proper training in "discovering" it are the best tools imo...... Look where conditions are right, ask about previous damage, look for signs of previous damge (funny paint texture, swollen base boards, discolored tackless, etc.). Finding and documenting mold on the initial inspection can save your ass and should always be on your mind.

If further detection devices are needed there is tape and air sampling equipment available...