Not much many being manufactured any more but some available from resellers.  Try not to buy a store demo lest you get one like my detector.  I went to the link in previous post and then did a search for some of the detectors listed and found them on ebay/amazon/???.
Many used one but many new or never powered.

  (You need to Login or Register;

Solotripper beat me to it and I like his better.