RE: Why join the AMA?
Virtually all clubs require it to fly or join.
Most public-owned fields require it.
$2 million liability insurance coverage.
A pretty good magazine.
Sanctioned events from coast-to-coast.
Not to mention the lobbying they do on behalf of the modeler to aquire and protect all the R/C radio frequencies you enjoy the use of. There's more, but that's enough to make me think it's a pretty good deal...