http://www.tesoro.com/
I have owned many from over $1500 and have found that the most simple featured ones under $500 (when you know what your doing) is the best .
First and foremost is that you have to have a very light one , if you intend to go at it like I do (all day long).
A headset designed for the detector you get is a must .
Not all headsets are equal in this field.
And a endless supply of the best battery's you can get .
I usually replace battery's every day and sometimes twice, if I'm at it hard.
And believe me that they need to be balanced properly as to keep from killing your arm at the end of the day.
Out of all I've owned I like this one best ...
http://www.tesoro.com/product/detectors/compadre/
At only 2.2 pound you will never get tired of using it.
It is only $189.00 . you can't go wrong for your first and maybe the last .
It goes with me everywhere.
Just my 2 cents.