Here is the one I bought on Amazon.Com from Climate Doctors for $208.99.
<a href="http://www.amazon.com/gp/product/B000BHNUI6/ref=as_li_tf_il?ie=UTF8&camp=1789&creative=9325&cr eativeASIN=B000BHNUI6&linkCode=as2&tag=affiliatech ie-20"><img border="0" src="http://ws.assoc-amazon.com/widgets/q?_encoding=UTF8&ASIN=B000BHNUI6&Format=_SL110_&ID =AsinImage&MarketPlace=US&ServiceVersion=20070822& WS=1&tag=affiliatechie-20" ></a><img src="http://www.assoc-amazon.com/e/ir?t=affiliatechie-20&l=as2&o=1&a=B000BHNUI6" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />
<a href="http://www.amazon.com/gp/product/B000BHNUI6/ref=as_li_tf_tl?ie=UTF8&camp=1789&creative=9325&cr eativeASIN=B000BHNUI6&linkCode=as2&tag=affiliatech ie-20">Mastercool 55100 Electronic Leak Detector</a><img src="http://www.assoc-amazon.com/e/ir?t=affiliatechie-20&l=as2&o=1&a=B000BHNUI6" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />