The ELF Zone is the most inexpensive AC EMF meter available, and you really get what you pay for here!
Three LED lights signal field strength:
Green: 0 - 2.5 mG  
Yellow: 2.5 - 7 mG  
Red: 8 or more mG

I hang on to this as a backup.
One of the reason I haven't invested more money in the EMF department is because I haven't  seen much
evidence as yet to support their usefulness one way of the other.

If you haven't already, head over
HERE and read Justin Faulk's articles on EMF meters.
I wish I had before spending a dime on EMF equipment.