Quite interesting thread over here at the Naviator forum, if anybody's
into computer stuff, etc. This is actually a pretty simple device to build,
and for probably under $100 you can get ADS-B IN for about an afternoon
projects worth of fooling around. It's not totally robust yet, but I bet with
a few more weeks time it will be.

http://forum.naviatorapp.com/viewtopic.php?id=1159

Jeff