Ok,
Let's break it down to what you are going to get out of the AMA membership.

A magazine that some say is decent (I personally like it)

A lobby group that protects our flying frequencies and watch other legislation that effects us.

A really nice place to go fly when you are in Muncie, In.

Ok ok, you can live without these
Liability insurance that will cover you in the event that you plane damages property or injures somebody.
In today's lawsuit happy world you could easily find yourself a million or so dollars in debt if you actually hit somebody with your plane and injure them. Hmmm, let's see $58 vs. $1,000,000 . In my opinion it's worth if for the insurance alone!!!!

Hope this helps

Ken