Those tools are abundant on ebay for $10 and up. Here's an example of a USA made version.
http://cgi.ebay.com/K-D-DOUBLE-FLAR..._DefaultDomain_0&hash=item20ba36b7dfI have a very basic KD double flaring tool that works perfectly on 3/16"-3/8" tubing and has made many brake, transmission cooler and fuel hard lines.