I recently got into flying model airplanes, and the whole AMA/club thing has me a bit confused. I've been flying my little electric Hobbyzone Super Cub at a local park. The park is about 25 acres and remains 99% empty except during sporting events (soccer, softball, etc), which makes it a pretty good site I think. While reading through the forums here, everyone seems to suggest that new pilots join a club to get instruction before flying. At $60 for the AMA plus $90 for membership/initiation/etc, it would cost more to fly the plane at a club field than to trash it at a park and buy another. Now here's my question... Is it necessary to join the AMA and a club to fly these little "park fliers"? And if not, at what point should a person feel compelled to start jumping through hoops and paying extra fees to fly?

I was hoping to get a small .40 powered sport plane next, and that's sort of why I'm asking. Can those be flown safely at a park? If so, how big is too big for park flying? The local club's field is bordered by a highway, so it doesn't seem much safer...