I bought a cheap umbrella hat. I figured it would do just fine. I was wrong. Oh, it's an okay umbrella hat, but it's a little uncomfortable, and one of the metal (tin?) pieces that attaches to the elastic band came loose.
I'll be buying a higher quality hat.
A cheap umbrella hat is all you need for membership, but you may want to spend a couple more dollars for a comfortable, reliable umbrella hat.
Just a little heads-up!